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                                                                       EXHIBIT 4
 
                                 March 14, 1999
 
The Board of Directors
Haskel International, Inc.
100 E. Graham Place
Burbank, CA 91502
 
Members of the Board of Directors:
 
     We understand that Haskel International, Inc. ("Haskel" or the "Company")
is contemplating a transaction pursuant to which HI Holdings Inc. ("HI
Holdings") would acquire all of the outstanding Class A and Class B shares (the
"Shares") of Common Stock of the Company (the "Transaction"). The Transaction
will be effected through a merger (the "Merger") by HI Merger Subsidiary, Inc.
("Acquisition Corp."), an indirect wholly-owned subsidiary of HI Holdings, with
the Company pursuant to which, among other things, (i) the Company would become
an indirect wholly-owned subsidiary of HI Holdings, (ii) each outstanding Share
(other than treasury Shares) would be converted into the right to receive $12.90
in cash (the "Transaction Consideration"), and (iii) concurrent with the
consummation of the Merger, the holder of each outstanding option to purchase
Shares not previously exercised would receive in cash, upon cancellation of such
option, an amount equal to the positive difference, if any, between $12.90 and
the exercise price per Share of such option multiplied by the number of Shares
subject to such option. The terms and conditions of the Transaction are more
fully described in the proposed Agreement and Plan of Merger (the "Merger
Agreement").
 
     You have requested that Schroder & Co. Inc. ("Schroders") render an opinion
(the "Opinion"), as investment bankers, as to the fairness, from a financial
point of view, of the Transaction Consideration to be received by the
stockholders of the Company.
 
     Schroders, as part of its investment banking business, is continually
engaged in the valuation of businesses and their securities in connection with
mergers and acquisitions, negotiated underwritings, secondary distributions of
listed and unlisted securities, private placements and valuations for estate,
corporate and other purposes. Schroders has acted as financial advisor to Haskel
with respect to the Transaction for which we will receive a fee for our
services, a significant portion of which is contingent upon consummation of the
Transaction.
 
     In connection with the Opinion set forth herein we have, among other
things:
 
- - reviewed a draft, dated March 14, 1999, of the Merger Agreement;
 
- - visited the executive offices and operations of the Company in Burbank, CA;
 
- - reviewed the Company's Annual Reports on Form 10-K for the fiscal years ended
  May 31, 1994 through 1998, including the audited consolidated financial
  statements contained therein;
 
- - reviewed the Company's Quarterly Report on Form 10-Q for the quarter ended
  November 30, 1998, including the unaudited consolidated financial statements
  contained therein;
 
- - reviewed historical financial results of the Company and its subsidiaries
  prepared by management;
 
- - had discussions with the senior management of the Company regarding the
  business, operations and prospects of the Company and its subsidiaries;
 
- - reviewed projections of the Company prepared by the management;
 
- - researched certain publicly available information on industry in which the
  Company operates;
 
- - performed various analyses, as we deemed appropriate, of the Company using
  generally accepted analytical methodologies, including (i) an analysis of
  premiums paid in public merger and acquisition transactions; (ii) the
  application of the public trading multiples of companies which we deemed
  comparable to the Company; (iii) the application of the multiples reflected in
  recent merger and acquisition transactions involving businesses which we
  deemed comparable to the financial results of the Company; and (iv)
  discounting the projected cash flows of the Company's operations;
 
- - solicited indications of interest from 103 potential buyers;
 
- - reviewed historical trading prices and volume of the Company's common stock;
  and
 
- - performed such of the financial studies, analyses, inquiries and
  investigations, as we deemed appropriate.