REGISTRATION RIGHTS AGREEMENT, dated as of February 28, 2002, between
MERRIMAC INDUSTRIES, INC., a Delaware corporation ("Merrimac"), and DUPONT
CHEMICAL AND ENERGY OPERATIONS, INC. ("DCEO"), a Delaware corporation and
wholly-owned subsidiary of E.I. DU PONT DE NEMOURS AND COMPANY, a Delaware
corporation ("DuPont").

         WHEREAS, Merrimac and DCEO have entered into a Subscription Agreement
(the "Subscription Agreement"), dated as of February 28, 2002, pursuant to which
Merrimac has issued and sold to DCEO, and DCEO has purchased from Merrimac,
528,413 shares of Merrimac's Common Stock (the "Shares"); and

         WHEREAS, as a condition to DCEO's obligations under the Subscription
Agreement, Merrimac is entering into this Agreement in order to provide DCEO
with certain rights to register the Shares.

         NOW, THEREFORE, the parties agree as follows:

1.     Definitions. As used in this Agreement, the following terms shall have
the following meanings:

         1.1 "Common Stock" means Merrimac's Common Stock, $0.01 par value per
share.

         1.2 "Exchange Act" means the Securities Exchange Act of 1934.

         1.3 "Form S-3" means such form under the Securities Act as in effect on
the date hereof or any successor form under the Securities Act.

         1.4 "Other Holders" means the Persons having registration rights with
respect to the Common Stock pursuant to the Other Registration Agreements.

         1.5 "Other Registration Agreements" means the registration rights
agreements between Merrimac and holders of securities of Merrimac other than
DCEO.

         1.6 "Person" shall mean any individual, sole proprietorship,
partnership, corporation, limited liability company, business trust,
unincorporated association, joint stock corporation, trust, joint venture or
other entity.

         1.7 "Registrable Shares" means all or any portion of the Shares, or
other shares of Common Stock issued to DCEO on or with respect to the Shares,
whether by reason of a stock split or share reclassification thereof, a stock
dividend thereon or otherwise; provided, that the Registrable Shares will cease
to be Registrable Shares when and to the extent that (a) a Registration
Statement covering such Registrable Shares has been declared effective under the
Securities Act and such Registrable Shares have been disposed of pursuant to
such effective Registration Statement, (b) such Registrable Shares are
distributed to the public pursuant to Rule 144 or (c) such Registrable Shares
are no longer held by DCEO or a permitted transferee under the Subscription
Agreement.





         1.8 "Registration Statement" means a registration statement of Merrimac
under the Securities Act on any form (to be selected by Merrimac) for which
Merrimac then qualifies and which permits the sale thereunder of the Registrable
Shares requested by DCEO pursuant to this Agreement to be included therein. The
term Registration Statement shall also include all exhibits and financial
statements and schedules and documents incorporated by reference in such
Registration Statement when it becomes effective under the Securities Act, and
in the case of references to the Registration Statement as of a date subsequent
to its effective date, as amended or supplemented as of such date.

         1.9 "Rule 144" means Rule 144 (or any successor provision then in
force) under the Securities Act, as promulgated by the SEC.

         1.10 "SEC" means the Securities and Exchange Commission.

         1.11 "Securities Act" means the Securities Act of 1933.

2.     Registration Rights.

         2.1 Demand Registrations.

                    (a) If Merrimac shall receive, at any time beginning 90
days prior to the second anniversary of the date hereof, a written request
from DCEO or a permitted transferee under the Subscription Agreement to file a
Registration Statement covering the registration of at least the lesser of (i)
50% of the Registrable Shares then outstanding or (ii) Registrable Shares
having an anticipated aggregate public offering price of at least $1.0
million, then Merrimac shall use its commercially reasonable efforts to file
as soon as practicable and to effect, within 90 days of the receipt of such
request, the registration under the Securities Act of all Registrable Shares
which DCEO requests to be registered. Merrimac shall not be obligated to
register any shares pursuant to this Section 2.1(a) after Merrimac has
effected two Registration Statements pursuant to this Section 2.1(a) and such
Registration Statements have been declared or ordered effective. Registration
Statements effected pursuant to Section 2.1(b) shall not affect the two
Registration Statements permitted under this Section 2.1(a).

                    (b) In addition to the registration rights provided
pursuant to Section 2.1(a), if Merrimac (i) shall receive, at any time
beginning 90 days prior to the second anniversary of the date hereof, a
written request from DCEO or a permitted transferee under the Subscription
Agreement to file a Registration Statement on Form S-3 covering the
registration of at least 50,000 shares of the Registrable Shares pursuant to a
non-underwritten offering and (ii) is entitled, at the time the registration
statement is requested, to use Form S-3 to register such shares, then Merrimac
shall use its commercially reasonable efforts to file as soon as practicable
and to effect, within 90 days of the receipt of such request, the registration
under the Securities Act on Form S-3 of all Registrable Shares which DCEO
requests to be registered. Merrimac shall not be obligated to register any
Registrable Shares pursuant to this Section 2.1(b) on more than two occasions
within any twelve-month period. Registration Statements effected pursuant to
Section 2.1(a) shall not affect the Registration Statements permitted under
this Section 2.1(b).

                    (c) If DCEO intends to distribute the Registrable Shares
covered by its request by means of an underwriting, it shall so advise
Merrimac as a part of its request made pursuant to Section 2.1(a) hereof. The
underwriters will be selected by Merrimac and shall be


                                       2



reasonably acceptable to DCEO. In such an event, the right of DCEO to include
the Registrable Shares in such Registration Statement shall be conditioned upon
DCEO entering into an underwriting agreement, in customary form, with the
underwriters.

                    (d) Notwithstanding the foregoing, if Merrimac shall
furnish to DCEO a certificate signed by the President of Merrimac stating
that, in the good faith judgment of the Board of Directors of Merrimac, it
would be seriously detrimental to Merrimac and its stockholders for such
Registration Statement to be filed, Merrimac shall have the right to defer
such filing for a period of not more than 60 days after receipt of the request
for registration pursuant to Section 2.1(a) or (b) hereof; provided, however,
that Merrimac may not utilize this Section 2.1(d) more than once in any
twelve-month period.

                    (e) Pursuant to the Other Registration Agreements,
Merrimac shall offer to the Other Holders the right to participate in and
include their securities in a Registration Statement required to be filed
pursuant to Section 2.1(a) or (b) hereof. In the event that an underwriting is
requested by DCEO pursuant to Section 2.1(c) hereof, the right of any Other
Holders to include their securities in such Registration Statement shall be
conditioned upon the inclusion of such Other Holders' securities in the
underwriting and their entering into an underwriting agreement, in customary
form, with the underwriters on substantially the same terms as DCEO's
agreement with the underwriters. Notwithstanding any other provision of this
Section 2.1, if the underwriters advise Merrimac in writing that marketing
factors require a limitation of the number of securities to be underwritten,
then Merrimac shall so advise DCEO and all Other Holders desiring to
participate in such offering. The amount of securities that may be included in
the underwriting shall be allocated, first, to all of the Shares requested to
be registered by DCEO and, second, if the underwriters approve, and there is
sufficient space left in the underwriting, among all Other Holders requesting
participation in such offering, in accordance with the provisions of the Other
Registration Agreements or, if no such provisions are applicable, pro rata,
based on the number of shares requested to be included therein by the Other
Holders. Any Registrable Shares excluded from such underwriting shall be
withdrawn from the Registration Statement.

                    (f) Merrimac shall not be obligated to file a Registration
Statement pursuant to this Section 2.1:

                          (i) if Merrimac has effected a registration pursuant
to an Other Registration Agreement within the 90-day period preceding such
request, during the period of 90 days after the effective date of such
registration; or

                          (ii) during the period starting with the date no more
than 30 days prior to Merrimac's good faith estimate of the date of filing of,
and ending on a date 90 days after the effective date of, a Registration
Statement pursuant to Section 2.2 hereof in which Merrimac is registering
securities for sale by it; provided, that (1) Merrimac is actively employing in
good faith all reasonable efforts to cause such Registration Statement to become
effective and (2) Merrimac has notified DuPont of its good faith estimate of
such period before or promptly after its commencement.

                    (g) Notwithstanding anything to the contrary contained in
any other provision of this Agreement, Merrimac shall not be required to
effect a registration under the Securities


                                       3



Act of an offering on a delayed or continuous basis pursuant to Rule 415 (or any
successor provision then in force) under the Securities Act (a "Shelf
Registration") or maintain the effectiveness of a Registration Statement to
effect a Shelf Registration.

         2.2 Piggyback Registration.

                    (a) If Merrimac proposes to register any of its securities
under the Securities Act whether (i) a registration for the sale of securities
by Merrimac (other than a registration relating solely to the sale of
securities to participants in a Merrimac stock option, stock issuance or other
incentive plan or a transaction covered by Rule 145 under the Securities Act)
or (ii) a demand registration effected by Merrimac for Other Holders pursuant
to the Other Registration Agreements (either such case, a "Piggyback
Registration"), Merrimac shall promptly give to DCEO written notice of such
registration, setting forth whether such registration is one in which Merrimac
is registering securities for sale by it or is pursuant to the demand of Other
Holders under Other Registration Agreements, including Merrimac's good faith
estimate of the date of filing of a registration statement for such
registration. Unless otherwise expressly prohibited by an Other Registration
Agreement pursuant to which a demand registration is being filed, Merrimac
shall, upon the written request of DCEO given within 20 days after receipt of
such notice from Merrimac, use its commercially reasonable efforts to register
under the Securities Act all of the Registrable Shares that DCEO has requested
to be registered. Merrimac agrees that no future Other Registration Agreement,
and no amendment to the current Other Registration Agreements, will contain
any limitations on DCEO's rights set forth in the preceding sentence not
contained in the Other Registration Agreements as currently in effect.

                    (b) If a Piggyback Registration is an underwritten
offering and the underwriters determine, in their opinion, that the total
number of shares requested to be offered and sold pursuant thereto would
jeopardize the success of such offering, then, if such registration is made
pursuant to demand registrations under Other Registration Agreements, the
number of shares that will be included in such registration shall be
allocated, first, to all of the securities to be offered by Merrimac, second,
to all of the shares the Other Holders, if any, have demanded be registered
pursuant to demand registrations made under Other Registration Agreements,
and, third, to the extent there is sufficient space, to all other stockholders
of Merrimac (including DCEO) requesting to have shares included in such
registration, on a pro rata basis, based on the number of shares requested to
be included therein. If a Piggyback Registration described in this Section
2.2(b) is not made pursuant to demand registrations under Other Registration
Agreements, the allocation shall be, first, to all of the securities to be
offered by Merrimac, and second, to the extent there is sufficient space, to
all other stockholders of Merrimac (including DCEO and the Other Holders)
requesting to have securities included in such registration, on a pro rata
basis, based on the number of shares requested to be included therein.

         2.3 Obligations of Merrimac. Whenever required under this Article 2 to
effect the registration of any Registrable Shares, Merrimac shall, as
expeditiously as reasonably practicable:

                    (a) Subject to Section 2.1(d), prepare and file with the
SEC a Registration Statement on any form for which Merrimac then qualifies or
which counsel for Merrimac deems appropriate, and DCEO's counsel in its
reasonable judgment, agrees, and use its commercially reasonable efforts to
cause such Registration Statement to become effective; and, upon the


                                       4



request of DCEO, keep such Registration Statement effective for a period ending
on the sooner to occur of 180 days or DCEO completing the distribution relating
thereto; provided, however, that such 180 days shall be extended for a period of
time equal to the period DCEO agrees to refrain from selling any Registrable
Shares included in such Registration Statement at the written request of
Merrimac in accordance with Section 2.4 hereof or an underwriter.

                    (b) Prepare and file with the SEC such amendments and
supplements to such Registration Statement and the prospectus used in
connection with such Registration Statement as may be necessary to comply with
the provisions of the Securities Act with respect to the disposition of all
securities covered by such Registration Statement.

                    (c) Furnish DCEO with such number of copies of the
prospectus, including a preliminary prospectus, in conformity with the
requirements of the Securities Act, and such other documents as it may
reasonably request in order to facilitate the disposition of the Registrable
Shares included in such Registration Statement.

                    (d) Use its commercially reasonable efforts to register
and qualify the Registrable Shares included in such Registration Statement
under such blue sky laws of such jurisdictions as shall be reasonably
requested by DCEO, provided that Merrimac shall not be required in connection
therewith or as a condition thereto to qualify to do business or to file a
general consent to service of process in any such states or jurisdictions in
which it is not required for business purposes to file or qualify.

                    (e) In the event of any underwritten public offering,
enter into and perform its obligations under an underwriting agreement, in
customary form, with the managing underwriter of such offering.

                    (f) Notify DCEO, when a prospectus relating to the
Registrable Shares included in a Registration Statement is required to be
delivered under the Securities Act, of the happening of any event as a result
of which such prospectus includes an untrue statement of a material fact or
omits to state a material fact required to be stated therein or necessary to
make the statements therein not misleading in the light of the circumstances
then existing and, as promptly as shall be practicable, correct such
prospectus.

                    (g) Cause all such Registrable Shares registered hereunder
to be listed on each securities exchange in which similar securities issued by
Merrimac are then listed.

                    (h) Provide a transfer agent and registrar for all
Registrable Shares registered hereunder and a CUSIP number for all such
Registrable Shares, in each case not later than the effective date of such
Registration Statement.

                    (i) Take such other commercially reasonable efforts as are
necessary to carry out its obligations hereunder.

         2.4 Delay of Effective Registration Statement. Upon receipt of written
notice from Merrimac of the happening of any event of the kind described in
Section 2.3(f), DCEO shall forthwith discontinue disposition of the Registrable
Shares pursuant to the Registration Statement covering such Registrable Shares
until DCEO receives copies of the supplemented or amended prospectus (at
Merrimac's expense), and, if so directed by Merrimac, DCEO shall


                                       5



deliver to Merrimac (at Merrimac's expense) all copies, other than permanent
file copies, of the then current prospectus then in DCEO's possession covering
such Registrable Shares.

         2.5 Furnish Information. It shall be a condition precedent to the
obligations of Merrimac to take any action pursuant to this Article 2 that DCEO
shall furnish to Merrimac such relevant information regarding itself, the
Registrable Shares held by it, and the intended method of disposition of such
securities, as shall be required to effect the registration of the Registrable
Shares.

         2.6 Expenses of Registration.

                    (a) Except as provided in Section 2.6(b), all expenses,
including all registration, filing and qualification fees, printers' and
accounting fees and fees and disbursements of counsel for Merrimac, shall be
borne by Merrimac in connection with the registration of the Registrable
Shares pursuant to Section 2.1 or 2.2; provided, however, that Merrimac shall
not be required to pay for any expenses of any registration proceeding begun
pursuant to Section 2.1 if the registration request is subsequently withdrawn
solely at the request of DCEO (in which case DCEO shall bear such
out-of-pocket expenses incurred in the preparation, filing and processing of
the Registration Statement), unless DCEO agrees to forfeit its right to one
demand registration pursuant to Section 2.1(a).

                    (b) DCEO will pay any fees or disbursements of its
counsel, and all underwriting discounts and commissions and transfer taxes, if
any, allocable to the Registrable Shares being registered, and other fees,
costs and expenses relating to the sale or disposition of the Registrable
Shares pursuant to a Registration Statement.

         2.7 Delay of Registration. DCEO agrees not to obtain or seek an
injunction restraining or otherwise delaying any such registration as the result
of any controversy that might arise with respect to the interpretation or
implementation of this Article 2.

         2.8 Indemnification. In the event any Registrable Shares are included
in a Registration Statement under this Article 2:

                    (a) To the extent permitted by law, Merrimac will
indemnify and hold harmless DCEO and any underwriter (as defined in the
Securities Act) for DCEO against any losses, claims, damages or liabilities
(joint or several) to which they may become subject under the Securities Act
or other federal or state law, insofar as such losses, claims, damages or
liabilities (or actions in respect thereof) arise out of or are based upon any
of the following statements, omissions or violations (collectively a
"Violation"): (i) any untrue statement or alleged untrue statement of a
material fact contained in such Registration Statement, including any
preliminary prospectus or final prospectus contained therein or any amendments
or supplements thereto, (ii) the omission or alleged omission to state therein
a material fact required to be stated therein, or necessary to make the
statements therein not misleading or (iii) any violation or alleged violation
by Merrimac of the Securities Act, any state securities law or any rule or
regulation promulgated under the Securities Act or any state securities law;
and Merrimac will pay to DCEO or such underwriter, as incurred, any legal or
other expenses reasonably incurred by them in connection with investigating or
defending any such loss, claim, damage, liability or action; provided,
however, that the indemnity agreement contained in this Section


                                       6



2.8(a) shall not apply to amounts paid in settlement of any such loss, claim,
damage, liability or action if such settlement is effected without the consent
of Merrimac (which consent shall not be unreasonably withheld), nor shall
Merrimac be liable in any such case for any such loss, claim, damage, liability,
or action to the extent that it arises out of or is based upon a Violation which
occurs (x) in reliance upon and in conformity with written information furnished
expressly for use in connection with such registration by DCEO or such
underwriter, (y) results from DCEO's failure to deliver a copy of the prospectus
or any amendments or supplements thereto after Merrimac has furnished DCEO with
a sufficient number of copies of same or (z) results from DCEO's delivery of
prospectuses after Merrimac has notified DCEO in writing to discontinue delivery
of such prospectuses pursuant to Section 2.4 hereof.

                    (b) To the extent permitted by law, DCEO will indemnify
and hold harmless Merrimac, each of its directors, officers, agents,
representatives and affiliates and any underwriter against any losses, claims,
damages or liabilities (joint or several) to which any of the foregoing
persons may become subject, under the Securities Act, the Exchange Act or
other federal or state law, insofar as such losses, claims, damages or
liabilities (or actions in respect thereto) arise out of or are based upon any
Violation, in each case to the extent, and only to the extent, that such
Violation occurs in reliance upon and in conformity with written information
furnished by DCEO expressly for use in connection with such registration; and
DCEO will pay, as incurred, any legal or other expenses reasonably incurred by
any person intended to be indemnified pursuant to this Section 2.8(b), in
connection with investigating or defending any such loss, claim, damage,
liability or action; provided, however, that the indemnity agreement contained
in this Section 2.8(b) shall not apply to amounts paid in settlement of any
such loss, claim, damage, liability or action if such settlement is effected
without the consent of DCEO, which consent shall not be unreasonably withheld;
provided, that, in no event shall any indemnity under this Section 2.8(b)
exceed the net proceeds from the offering received by DCEO, except in the case
of willful misconduct by DCEO.

                    (c) Promptly after receipt by an indemnified party under
this Section 2.8 of notice of the commencement of any action (including any
governmental action), such indemnified party will, if a claim in respect
thereof is to be made against any indemnifying party under this Section 2.8,
deliver to the indemnifying party a written notice of the commencement thereof
and the indemnifying party shall have the right to participate in, and, to the
extent the indemnifying party so desires, jointly with any other indemnifying
party similarly noticed, to assume the defense thereof with counsel mutually
satisfactory to the parties; provided, however, that an indemnified party
(together with all other indemnified parties which may be represented without
conflict by one counsel) shall have the right to retain one separate counsel
and to control its own defense, with the reasonable fees and expenses to be
paid by the indemnifying party, if representation of such indemnified party by
the counsel retained by the indemnifying party would be inappropriate due to
actual or potential differing interests between such indemnified party and any
other party represented by such counsel in such proceeding. The failure to
deliver written notice to the indemnifying party within a reasonable time of
the commencement of any such action, if materially prejudicial to its ability
to defend such action, shall relieve such indemnifying party of any liability
to the indemnified party under this Section 2.8, but the omission so to
deliver written notice to the indemnifying party will not relieve it of any
liability that it may have to any indemnified party otherwise than under this
Section 2.8.


                                       7



                    (d) If the indemnification provided for in this Section
2.8 is held by a court of competent jurisdiction to be unavailable to an
indemnified party with respect to any loss, liability, claim, damage or
expense referred to therein, then the indemnifying party, in lieu of
indemnifying such indemnified party hereunder, shall contribute to the amount
paid or payable by such indemnified party as a result of such loss, liability,
claim, damage or expense in such proportion as is appropriate to reflect the
relative fault of the indemnifying party on the one hand and of the
indemnified party on the other in connection with the statements or omissions
that resulted in such loss, liability, claim, damage or expense as well as any
other relevant equitable considerations; provided, that, in no event shall any
contribution by DCEO under this Section 2.8(d) exceed the net proceeds from
the offering received by DCEO, except in the case of willful misconduct by
DCEO. The relative fault of the indemnifying party and of the indemnified
party shall be determined by reference to, among other things, whether the
untrue or alleged untrue statement of a material fact or the omission to state
a material fact relates to information supplied by the indemnifying party or
by the indemnified party and the parties' relative intent, knowledge, access
to information, and opportunity to correct or prevent such statement or
omission.

                    (e) Notwithstanding the foregoing, to the extent that the
provisions on indemnification and contribution contained in the underwriting
agreement entered into in connection with the underwritten public offering are
in conflict with the foregoing provisions, the provisions in the underwriting
agreement shall control.

                    (f) The obligations of Merrimac and DCEO under this
Section 2.8 shall survive the completion of any offering of Registrable Shares
in a Registration Statement under this Article 2.

         2.9 Reports Under the Exchange Act. With a view to making available to
DCEO the benefits of Rule 144 and any other rule or regulation of the SEC that
may at any time permit DCEO to sell the Registrable Shares to the public without
registration or pursuant to a registration, Merrimac agrees to:

                    (a) make and keep public information available, as those
terms are defined in Rule 144, so long as Merrimac remains subject to the
periodic reporting requirements under Section 13 or 15(d) of the Exchange Act;

                    (b) use commercially reasonable efforts to file with the
SEC in a timely manner all reports and other documents required of Merrimac
under the Securities Act and the Exchange Act; and

                    (c) furnish to DCEO, so long as DCEO owns the Registrable
Shares, forthwith upon request (i) a written statement by Merrimac that it has
complied with the reporting requirements of Rule 144 and the Exchange Act,
(ii) a copy of the most recent annual or quarterly report of Merrimac and such
other reports and documents so filed by Merrimac, (iii) if requested by DCEO,
an opinion of counsel as to the availability of Rule 144 for DCEO to sell the
Registrable Shares and (iv) such other information as may be reasonably
requested in availing DCEO of any rule or regulation of the SEC which permits
the selling of any such securities without registration or pursuant to such
form.


                                       8



         2.10 Assignment of Registration Rights. The right to cause Merrimac to
register the Registrable Shares and other rights granted pursuant to this
Article 2 may only be assigned (and only subject to all related obligations) to
transferees permitted under the Subscription Agreement.

         2.11 Market Stand-Off Agreement. (a) With respect to a Registration
Statement in which Merrimac is registering securities for sale by it, or a
Piggyback Registration in which either DCEO has not requested any Shares be
included after having been offered such right or has had registered more than
50% of the Shares it requested to be so registered, DCEO agrees that, during the
period (up to, but not exceeding, 180 days) specified by Merrimac and an
underwriter, following the date of the final prospectus distributed in
connection with the Registration Statement, it shall not, to the extent
requested by Merrimac and such underwriter, directly or indirectly sell, offer
to sell, contract to sell (including, without limitation, any short sale), grant
any option to purchase or otherwise transfer or dispose of (other than to donees
and permitted assignees who agree to be similarly bound) any securities of
Merrimac held by it at any time during such period except Common Stock purchased
in the public offering and Common Stock purchased in an open market transaction;
provided, however, that all officers and directors of Merrimac and the Other
Holders enter into similar agreements; provided, further, that Merrimac may not
utilize this Section 2.11 more than once in any eighteen-month period.

                    (b) With respect to a Registration Statement other than
those described in Section 2.11(a), the provisions of Section 2.11(a) shall
apply to DCEO; provided, however, that DCEO may sell Shares held by it
pursuant to Rule 144 of the Securities Act after 30 days following the date of
the final prospectus distributed in connection with such Registration
Statement; and provided, further, that DCEO may exercise its rights under
Section 2.1 after 90 days following the date of the final prospectus
distributed in connection with such Registration Statement, but only to the
extent of the number of Shares it requested be registered in such Registration
Statement which was not so registered.

                    (c) In order to enforce the foregoing covenants, Merrimac
may impose stop-transfer instructions with respect to the Registrable Shares
until the end of such period, and DCEO agrees that, if so requested, it will
execute an agreement in the form provided by the underwriter containing terms
which are essentially consistent with the provisions of this Section 2.11.

                    (d) Notwithstanding the foregoing, the obligations
described in this Section 2.11 shall not apply to a registration relating
solely to employee benefit plans on Form S-1 or Form S-8 or similar forms
which may be promulgated in the future, or a registration relating solely to a
Rule 145 transaction on Form S-4 or similar forms which may be promulgated in
the future.

         2.12 Termination of Registration Rights. DCEO shall not be entitled to
exercise any right provided for in this Article 2 after such time as Rule 144 of
the Securities Act or another similar exemption under the Securities Act is
available for the sale of all of the Registrable Shares during a three month
period.

         2.13 Priority of Demands. For all purposes of this Article 2, any
registration demanded by DCEO pursuant to Section 2.1(a) or (b) shall have
priority over any registration


                                       9


subsequently demanded by an Other Holder pursuant to an Other Registration
Agreement, and any registration demanded by an Other Holder pursuant to an Other
Registration Agreement shall have priority over any registration subsequently
demanded by DCEO pursuant to Section 2.1 (a) or (b).

3.     Miscellaneous.

         3.1 Entire Agreement; Successors and Assigns. This Agreement, the
Subscription Agreement and the Employee Loan Agreement and Memorandum of
Understanding, dated as of February 28, 2000, between Merrimac and DCEO or
DuPont (collectively, the "Transaction Agreements") constitute the entire
agreement between the parties relating to the subject matter thereof and no
party shall be liable or bound to the other in any manner by any
representations, warranties or covenants except as specifically set forth
therein. Any previous agreement among the parties with respect to the
Registrable Shares is superseded by the Transaction Agreements. The terms of
this Agreement shall inure to the benefit of and be binding upon the respective
successors and permitted assigns of the parties. Except as expressly provided
herein, nothing in this Agreement, expressed or implied, is intended to confer
upon any party, other than the parties hereto, any rights, remedies, obligations
or liabilities under or by reason of this Agreement.

         3.2 Governing Law; Jurisdiction. This Agreement shall be governed by
and construed in accordance with the laws of the State of New York without
regard to principles of conflicts of law. Each party also waives any right to
trial by jury.

         3.3 Counterparts. This Agreement may be executed in counterparts, each
of which shall be deemed an original, but all of which together shall constitute
one and the same instrument.

         3.4 Headings. The headings of the sections of this Agreement are for
convenience and shall not by themselves determine the interpretation of this
Agreement.

         3.5 Notices. Any notice required or permitted hereunder shall be given
in writing and shall be deemed effectively given (i) upon personal delivery or
facsimile transmissions (with confirmation of receipt); (ii) five business days
after having been sent by registered or certified mail, return receipt
requested, postage prepaid; or (iii) one business day after deposit with a
nationally recognized overnight carrier, specifying next business day delivery,
with written verification of receipt, in each case, to the party to be notified
at such party's address as set forth in the Subscription Agreement or as
subsequently modified by written notice.

         3.6 Amendments and Waivers. Unless a particular provision or section of
this Agreement requires otherwise explicitly in a particular instance, any
provision of this Agreement may be amended and the observance of any provision
of this Agreement may be waived (either generally or in a particular instance
and either retroactively or prospectively), only with the written consent of
Merrimac and DCEO.

         3.7 Severability. In case any provision of this Agreement shall be
determined to be invalid, illegal or unenforceable, the validity, legality and
enforceability of the remaining provisions shall not in any way be affected or
impaired thereby.


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                IN WITNESS WHEREOF, the parties hereto have executed this
Registration Rights Agreement as of the date first written above.


                                            MERRIMAC INDUSTRIES, INC.


                                            By: /s/ Mason N. Carter
                                               ------------------------
                                            Name:  Mason N. Carter
                                            Title: Chairman, President and
                                                     Chief Executive Officer




                                            DUPONT CHEMICAL AND
                                            ENERGY OPERATIONS, INC.


                                            By: /s/ David B. Miller
                                               ------------------------
                                            Name:  David B. Miller
                                            Title: Attorney-in-fact










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