
                                                                 Exhibit (c)(4)






                                                              November 21, 1994



FKI plc
West House, King Cross Road
Halifax, West Yorkshire HX1 1EB
England
Attention:  S.D. Jones

Gentlemen:

         In connection with your consideration of a possible negotiated
transaction by you or one or more of your affiliates (as the term "affiliate" is
defined in the Securities Exchange Act of 1934, as amended (the "Exchange
Act")), involving The Crosby Group, Inc. ("Crosby"), a wholly-owned subsidiary
of Amdura Corporation ("Amdura," and together with Crosby, the "Company") (a
"Transaction"), the Company, Donaldson, Lufkin & Jenrette Securities Corporation
("DLJ"), acting as the Company's exclusive financial advisor in connection with
the proposed Transaction, and their respective advisors and agents are prepared
to make available to you certain information which is non-public, confidential
or proprietary in nature.

         By execution of this letter agreement (the "Agreement"), you agree to
treat confidentially all such information whether written or oral (the
"Evaluation Material"), and to observe the terms and conditions set forth
herein. You also agree that, subject to the fourth paragraph of this letter,
prior to giving any of your directors, officers, employees, partners,
affiliates, agents, advisors or representatives (hereinafter, "Representatives")
access to any of the Evaluation Material, you shall require each such
Representative to be bound by the terms of this Agreement to the same extent as
if they were parties hereto. You further agree to be responsible for any breach
of this Agreement by any of your Representatives.

         For purposes of this Agreement, Evaluation Material shall include,
without limitation, all information, data, reports, analyses, compilations,
studies, interpretations, projections, forecasts, records, and other materials
(whether prepared by the Company, DLJ or otherwise and in whatever form
maintained, whether documentary, computerized or otherwise), regardless of the
form of communication, that contain or otherwise reflect information concerning
the Company that you or your Representatives may be provided by or on behalf of
the Company or DLJ in the course of your evaluation of a possible Transaction.
The term "Evaluation Material" shall also include all information, data,
reports, analyses, computations, studies, interpretations, projections,
forecasts, records, notes, memoranda, summaries or other materials in whatever
form maintained, whether documentary, computerized or otherwise, whether
prepared by you or your Representatives or others, that contain or otherwise
reflect or are based upon, in whole or in part, any such Evaluation Material or
that reflect your review of, or interest in, all or any portion of the Company
(the "Notes"). This Agreement shall be inoperative as to those particular
portions of the Evaluation Material that (i) become generally available to the

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public other than as the result of a disclosure by you or any of your
Representatives, (ii) were available to you on a non-confidential basis prior to
the disclosure of such Evaluation Material to you pursuant to this Agreement,
provided that the source of such information was not known by you or any of your
Representatives, after reasonable investigation, to be bound by a
confidentiality agreement with or other contractual, legal or fiduciary
obligation of confidentiality to the Company or any of its affiliates with
respect to such material or (iii) become available to you on a non-confidential
basis from a source other than the Company or its agents, advisors or
representatives provided that the source of such information was not known by
you or any of your Representatives, after reasonable investigation, to be bound
by a confidentiality agreement with or other contractual, legal or fiduciary
obligation of confidentiality to the Company or any of its affiliates with
respect to such material.

         You agree that you will not use the Evaluation Material for any purpose
other than determining whether you wish to enter into a Transaction. You agree
not to disclose or allow disclosure to others of any Evaluation Material;
provided that, subject to the second paragraph of this agreement, you may
disclose Evaluation Material to your Representatives to the extent necessary to
permit such Representatives to assist you in making the determination referred
to in the prior sentence. You shall maintain a list of those of your
Representatives to whom Evaluation Material has been disclosed (which list shall
be presented to the Company upon request) and shall take all reasonable measures
(including but not limited to court proceedings), at your sole expense, to
restrain your Representatives from prohibited or unauthorized disclosure or use
of the Evaluation Material. In furtherance of the foregoing, you agree that you
will not use the Evaluation Material in any way directly or indirectly
detrimental to the Company. In particular you agree that for a period of 12
months from the date of the signing of this Agreement you and your affiliates
will not knowingly, as a result of knowledge or information obtained from the
Evaluation Material or otherwise in connection with a possible Transaction: (i)
divert or attempt to divert any business or customer of the Company or any of
its affiliates; nor (ii) employ or attempt to employ or divert an employee of
the Company or any of its affiliates.

         In addition, you agree that you will not make any disclosure (i) that
you, DLJ or the Company are having or have had discussions, or that you have
received Evaluation Material from the Company or DLJ concerning a Transaction,
(ii) that you are considering a possible Transaction or (iii) concerning any
discussions related to a possible Transaction, including the status thereof, any
termination thereof, any decision on your part to no longer consider any such
Transaction or any of the terms, conditions or other facts with respect thereto;
provided that you may make such disclosure if you have received the written
opinion of your counsel that such disclosure must be made by you in order that
you not commit a violation of law and, prior to such disclosure, you promptly
advise and consult with the Company and its legal counsel concerning the
information you propose to disclose. Without limiting the generality of the
foregoing, you further agree that, without the prior written consent of the
Company, you will not, directly or indirectly, enter into any agreement,
arrangement or understanding with any person regarding a possible Transaction.
The term "person" as used in this letter shall be broadly interpreted to
include, without limitation, the media and any corporation, partnership, group,
individual or other entity.

         Although the Company and DLJ have endeavored to include in the
Evaluation Material information known to them which they believe to be relevant
for the purpose of your investigation, you understand and agree that none of the
Company, DLJ or any of their affiliates, agents, advisors or representatives (i)
have made or make any representation or warranty, expressed or implied, as to

<PAGE>

the accuracy or completeness of the Evaluation Material or (ii) shall have any
liability whatsoever to you or your Representatives relating to or resulting
from the use of the Evaluation Material or any errors therein or omissions
therefrom.

         Without limiting the generality of the immediately preceding paragraph,
the Evaluation Material may include certain statements, estimates and
projections provided by the Company with respect to the anticipated future
performance of the Company. Such statements, estimates and projections reflect
various assumptions made by the Company concerning anticipated results, which
assumptions may or may not prove to be correct. No representations are made as
to the accuracy of such assumptions, statements, estimates or projections,
including the budget. The only information that will have any legal effect will
be specifically represented in a definitive purchase agreement; in no event will
such definitive agreement contain any representation as to the projections.

         In the event that you or anyone to whom you transmit any Evaluation
Material in accordance with this Agreement are requested or required (by
deposition, interrogatories, requests for information or documents in legal
proceedings, subpoenas, civil investigative demand or similar process), in
connection with any proceeding, to disclose any Evaluation Material, you will
give the Company prompt written notice of such request or requirement so that
the Company may seek an appropriate protective order or other remedy and/or
waive compliance with the provisions of this Agreement, and you will cooperate
with the Company to obtain such protective order. In the event that such
protective order or other remedy is not obtained or the Company waives
compliance with the relevant provisions of this Agreement, you (or such other
persons to whom such request is directed) will furnish only that portion of the
Evaluation Material which, in the written opinion of your counsel, is legally
required to be disclosed. It is further agreed that, if in the absence of a
protective order you (or such other persons to whom such request is directed)
are nonetheless legally compelled to disclose such information, you may make
such disclosure without liability hereunder, provided that you give the Company
notice of the information to be disclosed as far in advance of its disclosure as
is practicable and, upon the Company's request, use your best efforts to obtain
assurances that confidential treatment will be accorded to such information and,
provided further, that such disclosure was not caused by and did not result from
a previous disclosure by you or any of your Representatives not permitted
hereunder.

         If you decide that you do not wish to proceed with a Transaction, you
will promptly notify DLJ of that decision. In that case, or if the Company shall
elect at any time to terminate further access by you to the Evaluation Material
for any reason, you will within two business days redeliver to us all copies of
the Evaluation Material in the possession of you or your affiliates or your
Representatives, will destroy all Notes and will further deliver to DLJ and the
Company a certificate executed by one of your duly authorized executive officers
indicating that the requirements of this sentence have been satisfied in full.
Notwithstanding the return or destruction of Evaluation Material and Notes, you
and your Representatives will continue to be bound by your obligations of
confidentiality and other obligations hereunder.

         You hereby acknowledge that you are aware that the securities laws of
the United States prohibit any person who has material, non-public information
concerning the Company or a possible Transaction involving the Company from
purchasing or selling securities in reliance upon such information or from
communicating such information to any other person or entity under circumstances
in which it is reasonably foreseeable that such person or entity is likely to
purchase or sell such securities in reliance upon such information.

<PAGE>
         You agree that, for a period of three years from the date of this
agreement, unless such shall have been specifically invited in writing by the
Board of Directors of the Company, neither you nor any of your Representatives
will in any manner, directly or indirectly, (a) effect or seek, offer or propose
(whether publicly or otherwise) to effect, or cause or participate in or in any
way assist any other person to effect or seek, offer or propose (whether
publicly or otherwise) to effect or participate in, (i) any acquisition of any
securities (or beneficial ownership thereof) or assets of the Company or any of
its subsidiaries; (ii) any tender or exchange offer or merger or other business
combination involving the Company or any of its subsidiaries; (iii) any
recapitalization, restructuring, liquidation, dissolution or other extraordinary
transaction with respect to the Company or any of its subsidiaries; or (iv) any
"solicitation" of "proxies" (as such terms are used in the proxy rules of the
Securities and Exchange Commission) or consents to vote any voting securities of
the Company, (b) form, join or in any way participate in a "group" (as defined
under the Exchange Act), (c) otherwise act, alone or in concert with others, to
seek to control or influence the management, Board of Directors or policies of
the Company, (d) take any action which might force the Company to make a public
announcement regarding any of the types of matters set forth in (a) above, or
(3) enter into any discussions or arrangements with any third party with respect
to any of the foregoing. You also agree during any such period not to request
the Company (or its directors, officers, employees or agents), directly or
indirectly, to amend or waive any provision of this paragraph (including this
sentence).

         You understand that (i) the Company and DLJ shall conduct the process
for a possible Transaction as they in their sole discretion shall determine
(including, without limitation, negotiating with any prospective buyer and
entering into definitive agreements without prior notice to you or any other
person), (ii) any procedures relating to such a Transaction may be changed at
any time without notice to you or any other person, (iii) the Company shall have
the right to reject or accept any potential buyer, proposal or offer, for any
reason whatsoever, in its sole discretion, and (iv) neither you nor any of your
Representatives shall have any claims whatsoever against the Company or DLJ or
any of their respective directors, officers, stockholders, owners, affiliates or
agents arising out of or relating to the Transaction (other than those against
the parties to a definitive agreement with you in accordance with the terms
thereof).

         It is further understood and agreed that DLJ will arrange for
appropriate contacts for due diligence purposes. It is also understood and
agreed that all (i) communications regarding a possible Transaction, (ii)
requests for additional information, (iii) requests for facility tours or
management meetings and (iv) discussions or questions regarding procedures, will
be submitted or directed exclusively to DLJ, and that none of your or your
Representatives who are aware of the Evaluation Material and/or the possibility
of a Transaction will initiate or cause to be initiated any communication with
any director, officer or employee of the Company concerning the Evaluation
Material or a Transaction.

         You agree that unless and until a definitive agreement between the
Company and you with respect to any Transaction has been executed and delivered,
neither the Company nor you will be under any legal obligation of any kind
whatsoever with respect to such Transaction.

<PAGE>

         You agree that money damages would not be a sufficient remedy for any
breach of this Agreement by you or your Representatives, that in addition to all
other remedies the Company shall be entitled to specific performance and
injunctive or other equitable relief as a remedy for any such breach, and you
further agree to waive, and to use your best efforts to cause your
Representatives to waive, any requirement for the securing or posting of any
bond in connection with such remedy. In the event of litigation relating to this
letter agreement, if a court of competent jurisdiction determines that you or
any of your Representatives have breached this letter agreement, you shall be
liable and pay to the Company the reasonable legal fees incurred by the Company
in connection with such litigation, including any appeal therefrom.

         The Company reserves the right to assign its rights, powers and
privileges under this letter agreement (including, without limitation, the right
to enforce the terms of this letter agreement) to any person who enters into a
Transaction.

         All modifications of, waivers of and amendments to this Agreement or
any part hereof must be in writing signed on behalf of you and the Company or by
you and DLJ, as agent for the Company. You acknowledge that the Company is
intended to be benefited by this Agreement and that the Company shall be
entitled, either alone or together with DLJ, to enforce this Agreement and to
obtain for itself the benefit of any remedies that may be available for the
breach hereof.

         It is further understood and agreed that no failure or delay by the
Company in exercising any right, power or privilege under this Agreement shall
operate as a waiver thereof nor shall any single or partial exercise thereof
preclude any other or further exercise of any right, power or privilege
hereunder.

         You hereby irrevocably and unconditionally submit to the exclusive
jurisdiction of any State or Federal court sitting in New York City over any
suit, action or proceeding arising out of or relating to this letter. You hereby
agree that service of any process, summons, notice or document by U.S.
registered mail addressed to you shall be effective service of process for any
action, suit or proceeding brought against you in any such court. You hereby
irrevocably and unconditionally waive any objection to the laying of venue of
any such suit, action or proceeding brought in any such court and any claim that
any such suit, action or proceeding brought in any such court has been brought
in an inconvenient forum. You agree that a final judgment in any such suit,
action or proceeding brought in any such court shall be conclusive and binding
upon you and may be enforced in any other courts to whose jurisdiction you are
or may be subject, by suit upon such judgment.

         In the event that any provision or portion of this letter is determined
to be invalid or unenforceable for any reason, in whole or in part, the
remaining provisions of this letter shall be unaffected thereby and shall remain
in full force and effect to the fullest extent permitted by applicable law.

         This Agreement shall be governed by, and construed and enforced in
accordance with, the laws of the State of New York.





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         If you are in agreement with the foregoing, please so indicate by
signing, dating and returning one copy of this Agreement, which will constitute
our agreement with respect to the matters set forth herein.

                                           Very truly yours,



                                           AMDURA CORPORATION


                                           By:  /s/ Benoit Jamar
                                               ----------------------------
                                                Benoit Jamar
                                           DONALDSON, LUFKIN & JENRETTE
                                            SECURITIES CORPORATION
                                           as Exclusive Agent

AGREED AND ACCEPTED:

FKI plc


By:  /s/  Steven D. Jones
    ----------------------------------
Title:  Director of Corporate Planning

Date:  22/11/94


