STOCK PURCHASE AGREEMENT

          THIS STOCK PURCHASE  AGREEMENT is entered into as of June , 2003 (this
"Agreement"),  by Aearo  Corporation,  a Delaware  corporation  (the "Company"),
Cabot  Corporation,  a  Delaware  corporation  ("Cabot  Parent"),  and Cabot CSC
Corporation, a Delaware corporation and a wholly owned subsidiary of Cabot
Parent ("Cabot Sub" and, together with Cabot Parent, "Cabot").

                              W I T N E S S E T H :

          WHEREAS,  Cabot Sub owns  beneficially  and of record 42,500 shares of
common  stock,  par value  $.01 per  share,  and  22,500  shares  of  redeemable
preferred stock, $.01 per share, of the Company (collectively, the "Shares");

          WHEREAS,  the Company has agreed to purchase,  and Cabot has agreed to
sell, the Shares, and all accrued dividends thereon,  upon the terms and subject
to the conditions set forth herein;

          NOW, THEREFORE,  in consideration of the premises and mutual covenants
and agreements  hereinafter set forth,  the receipt and sufficiency of which are
hereby acknowledged, the parties hereto agree as follows:

1.  Purchase and Sale of Shares.  Subject to the  satisfaction  or waiver of the
conditions  set forth herein,  at the  ---------------------------  closing (the
"Closing"),  Cabot shall sell and the Company shall purchase the Shares, and all
accrued dividends thereon, for the consideration described below.

2.  Consideration.  The aggregate purchase price for the Shares, and all accrued
dividends  thereon,  shall be the sum of $33.5  million plus an amount,  if any,
equal to the excess,  if any, of (x) $5 million over (y) the aggregate amount of
fees and other out-of-pocket expenses incurred by the Company in connection with
the  consummation of the transactions  contemplated  hereby,  including  without
limitation consent fees payable to lenders and debt securityholders,  commitment
and other financing fees, and fees and expenses of professional  advisors to the
Company and its creditors  (the "Purchase  Price").  The Purchase Price shall be
payable by wire transfer of immediately  available funds to such bank account as
shall be  designated  by Cabot in writing at least three  business days prior to
Closing.

3. Deliveries. Cabot Sub will deliver or cause to be delivered to the Company at
the Closing stock  certificates  representing all of the Shares,  accompanied by
stock powers duly executed in blank or duly  executed  stock  transfer  forms or
instruments of transfer which validly transfer title to such Shares. The Company
will deliver to Cabot at the Closing the Purchase Price.

4.  Cabot's  Representations  and  Warranties.  Cabot  Parent and Cabot Sub each
represents  and  warrants to the Company  --------------------------------------
that:

(a)       each of them is duly  incorporated and in good standing under the laws
          of the jurisdiction of its incorporation;  Cabot Sub is the sole owner
          of the Shares and has good title to such Shares, free and clear of all
          liens, claims,  encumbrances and restrictions of every kind other than
          those  imposed by the  Stockholders'  Agreement,  dated July 11, 1995,
          among Vestar  Equity  Partners,  L.P.,  Cabot  Parent,  Cabot Sub, the
          Company, the Seelig Family Lifetime Trust and the Management Investors
          (as  defined  in  the  Stockholders'  Agreement),  as  amended  by the
          Amendment,  dated July 3, 1996 (the "Stockholders'  Agreement"),  and,
          upon completion of the transactions  contemplated  hereby,  such title
          will pass to the Company; and each of them has all requisite power and
          authority  to execute and deliver this  Agreement  and an amendment to
          the  Stockholders'  Agreement in  substantially  the form set forth on
          Exhibit A hereto (the "Amendment") and, subject to the satisfaction of
          the  conditions  set forth  herein,  to  consummate  the  transactions
          contemplated hereby; and

(b)       this Agreement  constitutes the legal, valid and binding obligation of
          each of them,  enforceable in accordance with its terms, except as the
          enforceability  thereof  may be  limited  by  bankruptcy,  insolvency,
          reorganization,  moratorium  or other laws now or  hereafter in effect
          relating  to or  limiting  creditors'  rights  generally  and  general
          principles of equity (whether  considered in an action in equity or at
          law).

5. The Company's  Representations  and  Warranties.  The Company  represents and
warrants to Cabot that: --------------------------------------------

(a)       it is duly  incorporated  and in good  standing  under the laws of the
          jurisdiction of its incorporation;  and it has all requisite power and
          authority to execute and deliver this Agreement and the Amendment and,
          subject to the  satisfaction  of the conditions  set forth herein,  to
          consummate the transactions contemplated hereby; and

(b)       this Agreement  constitutes its legal,  valid and binding  obligation,
          enforceable in accordance with its terms, except as the enforceability
          thereof  may be limited  by  bankruptcy,  insolvency,  reorganization,
          moratorium  or other laws now or  hereafter  in effect  relating to or
          limiting  creditors' rights generally and general principles of equity
          (whether considered in an action in equity or at law).

6. Covenants. ---------

(a)       Each  party  shall  pay  its  own  expenses  in  connection  with  the
          transactions  contemplated  hereby  whether  or not  the  transactions
          contemplated hereby are consummated.

(b)       Subject to the terms and conditions hereof, each of the parties hereto
          agrees to use its  reasonable  best  efforts  to take,  or cause to be
          taken,  all  actions,  and to do,  or  cause to be  done,  all  things
          necessary  to  consummate   and  make   effective   the   transactions
          contemplated  hereby,  including,  without  limitation,  obtaining the
          consents  set forth on Schedule 1 hereto (the  "Requisite  Consents");
          provided,  however, that with respect to the Requisite Consents, Cabot
          shall not be required to undertake  any  affirmative  effort or to pay
          any cost or expense, all of which shall be undertaken and borne by the
          Company.

(c)       The  Company   shall  pay  Cabot  all  accrued  and  unpaid  Fees  and
          Out-of-Pocket  Expenses payable to Cabot under (and as those terms are
          defined in) the  Management  Advisory  Agreement  dated as of July 11,
          1995 among  Cabot,  the  Company  and  Vestar  Capital  Partners  (the
          "Management Agreement"); provided that notwithstanding anything in the
          Management  Agreement to the  contrary,  within 30 days after the last
          day of the month in which the  Closing  occurs,  the  semi-annual  Fee
          payment  next  paid to Cabot  shall be  pro-rated  through  the day of
          Closing  and  adjusted   through  that  day  in  the  same  manner  as
          semi-annual Fee payments are adjusted under the Management  Agreement,
          and Cabot shall pay the  Company an amount  equal to the excess of the
          next  semi-annual  Fee payment  paid to Cabot over the  aforementioned
          pro-rated and adjusted Fee.

7. Conditions. ----------

(a)       The  obligation of Cabot to consummate the  transactions  contemplated
          hereby shall be subject to the  satisfaction at or prior to Closing of
          each of the following conditions:

                    (i)  the  representations  and  warranties  of  the  Company
          contained  herein  shall be true and correct on the date hereof and on
          the date of Closing,  and the Company shall have  performed all of its
          covenants contained herein to be performed prior to Closing;

                    (ii) the  approval of this  Agreement  and the  transactions
          contemplated hereby by Cabot Parent's Board of Directors;

                    (iii) on the date of  Closing,  there  shall be no decree of
          any governmental or judicial authority of competent  jurisdiction that
          prohibits the occurrence of the Closing; and

                    (iv)  the  Amendment  shall  have  been  duly  executed  and
          delivered by the parties  (other than Cabot)  specified in Section 5.5
          of the Stockholders' Agreement.

(b) The  obligation of the Company to consummate the  transactions  contemplated
hereby  shall be subject to the  satisfaction  at or prior to Closing of each of
the following conditions.

                    (i) the  representations  and warranties of Cabot  contained
          herein shall be true and correct on the date hereof and on the date of
          Closing, and Cabot shall have performed all of its covenants contained
          herein to be performed prior to Closing;

                    (ii) the  approval of this  Agreement  and the  transactions
          contemplated hereby by the Company's Board of Directors;

                    (iii) the Company's receipt of all Requisite Consents;

                    (iv) the Company shall have  received  proceeds of financing
          sufficient  to pay the  Purchase  Price  and any  other  out-of-pocket
          expenses  incurred by the Company in connection with the  transactions
          contemplated hereby on terms reasonably satisfactory to the Company;

                    (v) on the date of Closing,  there shall be no decree of any
          governmental  or judicial  authority  of competent  jurisdiction  that
          prohibits the occurrence of the Closing; and

                    (vi)  the  Amendment  shall  have  been  duly  executed  and
          delivered by the parties (other than the Company) specified in Section
          5.5 of the Stockholders' Agreement.

8.   Termination.   This  Agreement  may  be  terminated  and  the  transactions
contemplated  hereby  may be  abandoned  at any  -----------  time  prior to the
Closing as follows:

(a) by mutual written consent of the parties;

(b) by either the Company or Cabot in writing,  if the Closing has not  occurred
on or before September 30, 2003;

(c) by the Company in writing,  if the conditions set forth in Sections 7(b)(ii)
and 7(b)(vi) shall not have been satisfied on or before July 12, 2003; and

(d) by Cabot in writing,  if the conditions  set forth in Sections  7(a)(ii) and
7(a)(iv) shall not have been satisfied on or before July 12, 2003.

9.  Governing  Law.  This  Agreement  shall  be  governed  by and  construed  in
accordance  with the laws of the State of New  -------------  York applicable to
contracts made and to be performed therein.

10. Amendment;  Waiver. No change or modification of this Agreement or waiver of
any provision  hereof shall be valid  -----------------  unless it is in writing
and signed by each of the parties.

11. Entire Agreement.  This Agreement shall supersede all previous  negotiations
and agreements between the parties, and shall constitute the entire agreement of
the parties, with respect to the subject matter hereof. This Agreement shall not
supercede any other agreements or obligations of the parties hereto with respect
to other  subject  matters,  including  without  limitation  obligations  of the
parties with respect to  confidentiality  and under Sections 4.12 and 8.1 of the
Asset Transfer  Agreement,  dated as of June 13, 1995,  among the parties hereto
and certain other  persons,  and such other  agreements  and  obligations  shall
remain in full force and effect.

12. Survival.  The  representations,  warranties and covenants  contained herein
shall survive the Closing. --------

13. Closing Date.  Unless this Agreement shall have been terminated  pursuant to
Section 8, and subject to the satisfaction or waiver of the conditions set forth
herein,  the  Closing  shall  take  place  substantially  concurrently  with the
satisfaction or waiver of each of the conditions set forth herein at the offices
of Simpson Thacher & Bartlett LLP, 425 Lexington Avenue, New York, NY 10017.

14.  Notices.  All  notices,  and other  communications  required  or  permitted
hereunder  shall be in  writing  and shall be  -------  deemed to have been duly
given if delivered  personally,  telecopied,  emailed,  or mailed,  certified or
registered mail with postage prepaid, as follows:

                  If to the Company:
                  Aearo Corporation
                  5457 W. 79th Street
                  Indianapolis, IN  46268
                  Attn:  Jeffrey Kulka
                  Tel.:    (317) 692-6983
                  Fax:     (317) 692-6784
                  Email:   Jeff_Kulka@aearo.com

                  with a copy to:
                  Simpson Thacher & Bartlett LLP
                  425 Lexington Avenue, 12th Floor
                  New York, NY  10017-3954
                  Attn:  Peter J. Gordon
                  Tel:     (212) 455-2605
                  Fax:     (212) 455-2827
                  Email:  pgordon@stblaw.com
                          ------------------

                  If to Cabot;
                  Cabot Corporation
                  Two Seaport Lane
                  Suite 1300
                  Boston, MA  02210
                  Attn:    Ho-il Kim
                  Tel.:    617-342-6172
                  Fax:     617-342-6039
                  Email:  hoil_kim@cabot-corp.com

                  With a copy to:
                  Cabot Corporation
                  Two Seaport Lane
                  Suite 1300
                  Boston, MA  02210
                  Attn:    Philip J. Szabla
                  Tel.:    617-342-6179
                  Fax:     617-342-6073
                  Email:  philip_szabla@cabot-corp.com

or to such other person or address or telecopy  number as a party shall  specify
in writing. All such communications shall be deemed to have been received on the
date of personal  delivery,  on the third  business day after mailing or, in the
case of notice by telecopier or email, when receipt is confirmed by telephone.

15. Counterparts.  This Agreement may be executed in any number of counterparts,
each of which shall be deemed to be  ------------  an original  and all of which
together shall be deemed to be one instrument.






          IN WITNESS  WHEREOF,  the  undersigned  have set their hands as of the
date first written above.

                                    SELLER:

                                    CABOT CORPORATION


                                    By: ________________________________________
                                         Name:
                                         Title:


                                    CABOT CSC CORPORATION


                                    By: ________________________________________
                                         Name:
                                         Title:


                                    PURCHASER:

                                    AEARO CORPORATION


                                    By: ________________________________________
                                         Name:
                                         Title:





                                   Schedule 1

                               Requisite Consents

Consent of lenders under the Credit Agreement,  dated as of July 11, 1995, among
Aearo Company,  the Company and the  Subsidiary  Borrowers  named  therein,  the
lenders and arrangers  listed therein and Bankers Trust Company,  as co-arranger
and administrative agent, as amended and restated as of July 13, 2001.

Consent of holders of 12.5% Senior Subordinated Notes due 2005.





                                    Exhibit A

                  Form of Amendment to Stockholders' Agreement

          AMENDMENT TO STOCKHOLDERS' AGREEMENT,  dated as of June __, 2003 (this
"Amendment"),   among  Vestar  Equity  Partners,  L.P.  ("Vestar"),   Cabot  CSC
Corporation,  formerly  known  as  Cabot  Safety  Corporation  ("Cabot"),  Aearo
Corporation,  formerly known as Cabot Safety Holdings Corporation  ("Holdings"),
Cabot  Corporation  ("Cabot  Parent"),  the Seelig Family Lifetime Trust and the
parties  identified on the signature  pages hereto as Management  Investors (the
"Management Investors").

                              W I T N E S S E T H :
                              - - - - - - - - - -

          WHEREAS,  the  signatories  hereto  desire to amend the  Stockholders'
Agreement,  dated July 11, 1995, as amended by the Amendment, dated July 3, 1996
(the "Stockholders' Agreement"), as set forth below;

          NOW,   THEREFORE,   in  consideration  of  the  mutual  covenants  and
agreements herein contained, the parties hereto agree as follows:

B. Section 3.4(d) of the Stockholders'  Agreement is hereby amended by adding at
the end thereof the following new sentence:


          "Notwithstanding   anything  to  the  contrary  provided  herein,  the
          requirements  set forth in  Section  3.4(a)  and  3.4(b)  shall not be
          applicable  to any  Transfer of Common  Stock and  Preferred  Stock by
          Cabot to Holdings pursuant to the Stock Purchase Agreement, dated June
          __, 2003, among Holdings, Cabot and Cabot Parent."

C. Except as specifically  amended  hereby,  the  Stockholders'  Agreement shall
remain unchanged and continue in full force and effect.


                    [Remainder of page intentionally blank.]





          IN  WITNESS  WHEREOF,  each  of  the  undersigned  has  executed  this
Agreement  or caused this  Agreement to be executed on its behalf as of the date
first written above.

                                       VESTAR EQUITY PARTNERS, L.P.

                                       By:      Vestar Associates, L.P.,
                                                its general partner

                                       By:      VESTAR ASSOCIATES CORPORATION,
                                                its general partner


                                       By:_____________________________
                                                Name:
                                                Title:


                                       CABOT CSC CORPORATION

                                       By:_____________________________
                                                Name:
                                                Title:


                                       AEARO CORPORATION


                                       By:_____________________________
                                                 Name:
                                                 Title:


                                       CABOT CORPORATION


                                       By:_____________________________
                                                  Name:
                                                  Title:







                                       SEELIG FAMILY LIFETIME TRUST

                                       By:_____________________________
                                            Name: Leonard Lieberman
                                            Title: Trustee

                                       MANAGEMENT INVESTORS:

                                       By:_____________________________
                                             Name:



                                       By:_____________________________
                                             Name:



                                       By:_____________________________
                                             Name:



                                       By:_____________________________
                                              Name:



                                       By:_____________________________
                                              Name:



                                       By:_____________________________
                                              Name: