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                                                                     EXHIBIT 4.5

                          AMENDMENT TO RIGHTS AGREEMENT

         AMENDMENT, dated as of December 24, 1998 (this "Amendment"), to the
Rights Agreement, dated as of November 23, 1998 (the "Rights Agreement"), by and
between COHR Inc., a Delaware corporation (the "Company"), and ChaseMellon
Shareholder Services LLC, a New Jersey limited liability company, as Rights
Agent (the "Rights Agent").

         WHEREAS, shortly following the execution of this Amendment, the Three
Cities Fund II L.P. and Three Cities Offshore II C.V. (collectively, the "Three
Cities Funds") will purchase from funds managed by Franklin Research, Inc. and
by Strong Capital Management, Inc. an aggregate of 3,085,425 shares of common
stock, par value $.01 per share (the "Common Stock"), of the Company, which
constitutes approximately 48% of the total issued and outstanding Common Stock
as of the date hereof (the "Initial Purchase");

         WHEREAS, the Three Cities Funds are the sole stockholders of TCF
Acquisition Corporation, a Delaware corporation ("Acquisition");

         WHEREAS, shortly following the execution of this Amendment, the Company
and Acquisition will enter into that certain Plan and Agreement of Merger (the
"Merger Agreement") pursuant to which Acquisition will agree, among other
things, to make a tender offer for all outstanding shares of Common Stock (the
"Tender Offer") and, if Acquisition, the Three Cities Funds, and any other
stockholders of Acquisition collectively own 85% or greater of the Common Stock
following consummation of such tender offer, to merge Acquisition with and into
the Company (the "Merger");

         WHEREAS, it is in the best interests of the holders of the Common Stock
that the Rights Agreement be amended as set forth herein; and

         WHEREAS, Section 26 of the Rights Agreement provides that prior to the
Distribution Date (as defined in the Rights Agreement), the Company may, and the
Rights Agent shall if the Company so directs, supplement or amend any provision
of the Rights Agreement without the approval of the holders of Common Stock;

         NOW, THEREFORE, in consideration of the premises and the mutual
agreements herein set forth, the parties agree to amend the Rights Agreement as
follows:

         1. The first sentence of the definition of "Acquiring Person" in
Section 1 of the Rights Agreement is hereby amended to read in its entirety as
follows:

                  "Acquiring Person" shall mean any Person who or which, alone
         or together with all Affiliates and Associates of such Person, shall be
         the Beneficial Owner of more than 15% of the Common Shares then
         outstanding, but shall not include (a) the Company, any Subsidiary of
         the Company, any employee benefit plan of the Company or of any of its
         Subsidiaries, or any Person holding Common Shares for or pursuant to
         the terms of any such employee benefit plan; (b) any such Person who
         has become such a Beneficial Owner 

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         solely because (i) of a change in the aggregate number of Common Shares
         outstanding since the last date on which such Person acquired
         Beneficial Ownership of any Common Shares or (ii) (A) it acquired such
         Beneficial Ownership in the good faith belief that such acquisition
         would not (x) cause such Beneficial Ownership to exceed 15% of the
         Common Shares then outstanding and such Person relied in good faith in
         computing the percentage of its Beneficial Ownership on publicly filed
         reports or documents of the Company which are inaccurate or out-of-date
         or (y) otherwise cause a Distribution Date or the adjustment provided
         for in Section 11(a) to occur, or (B) it otherwise inadvertently
         acquired such Beneficial Ownership; or (c) the Three Cities Funds,
         together with all of its Affiliates and Associates, from and after
         consummation of the Initial Purchase but only until the earlier of the
         occurrence of the Three Cities Funds, together with all of its
         Affiliates and Associates, ceasing to own 15% of the Common Shares
         outstanding.

         2. The definition of "Expiration Date" in Section 1.1 of the Rights
Agreement is hereby amended to read in its entirety as follows:

                  "Expiration Date" shall mean the earlier of (i) if, after
         Acquisition (as defined in the Amendment to Rights Agreement, dated as
         of December 24, 1998, by and between the Company and the Rights Agent)
         purchases all Common Shares of the Company which are properly tendered
         in response to the Tender Offer and not withdrawn, Acquisition, the
         Three Cities Funds, and any other stockholders of Acquisition
         collectively own eighty-five percent (85%) or greater of the total
         outstanding Common Shares of the Company as of the Expiration Time (as
         defined in the Merger Agreement), the Close of Business on the date on
         which Acquisition consummates such purchases of Common Shares pursuant
         to the Tender Offer, and (ii) the Close of Business on the 10th
         anniversary of the date of the Rights Agreement.

         3. Effective immediately following the Initial Purchase, the definition
of "Grandfathered Stockholder" in Section 1.1 is hereby deleted from the Rights
Agreement and all references to "Grandfathered Stockholder" in the Rights
Agreement are hereby deleted.

         4. The first sentence of Section 3(b) of the Rights Agreement is hereby
amended to read in its entirety as follows:

         Until the earlier of (i) such time as the Company learns that a Person
         has become an Acquiring Person or (ii) the Close of Business on such
         date, if any, as may be designated by the Board of Directors of the
         Company following the commencement of, or first public disclosure of an
         intent to commence, a tender or exchange offer by any Person (other
         than Acquisition as contemplated by the Merger Agreement, the Company,
         any Subsidiary of the Company, any employee benefit plan of the Company
         or of any of its Subsidiaries, or any Person holding Common Shares for
         or pursuant to the terms of any such employee benefit plan) for
         outstanding Common Shares, if upon consummation of such tender or
         exchange offer such Person could be the Beneficial Owner of more than
         15% of the outstanding 

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         Common Shares (the Close of Business on the earlier of such dates being
         the "Distribution Date"), (x) the Rights will be evidenced by the
         certificates for Common Shares registered in the names of the holders
         thereof and not by separate Right Certificates and (y) the Rights,
         including the right to receive Right Certificates, will be transferable
         only in connection with the transfer of Common Shares.

         5.  Section 7(a) of the Rights Agreement is hereby amended to read in
its entirety as follows:

                  (a) Subject to Section 7(e) and except as otherwise provided
         herein (including Section 11), each Right shall entitle the registered
         holder thereof, upon exercise thereof as provided herein, to purchase
         for the Purchase Price, at any time after the Distribution Date and at
         or prior to the earlier of (i) the Expiration Date, or (ii) the
         Redemption Date, one one-thousandth (1/1000th) of a Preferred Share,
         subject to adjustment from time to time as provided in Sections 11 and
         12.

         6.  Section 21 of the Rights Agreement is hereby amended by adding the
following to the end of Section 21(j) thereof:

         The indemnity provided herein shall survive the termination of this
         Agreement and the termination and the expiration of the Rights. The
         costs and expenses incurred in enforcing this right of indemnification
         shall be paid by the Company. Anything to the contrary notwithstanding,
         in no event shall the Rights Agent be liable for special, punitive,
         indirect, consequential or incidental loss or damage of any kind
         whatsoever (including but not limited to lost profits), even if the
         Rights Agent has been advised of the likelihood of such loss or damage.
         Any liability of the Rights Agent under this Rights Agreement will be
         limited to the amount of fees paid by the Company to the Rights Agent.

         7.  For the avoidance of doubt and notwithstanding anything to the
contrary in the Rights Agreement (including this Amendment), it is the intent of
the parties that so long as the Three Cities Funds, together with all of its
Affiliates and Associates (including, without limitation, Acquisition), is not
an "Acquiring Person," no transaction contemplated by the Merger Agreement will
cause a Distribution Date under the Rights Agreement.

         8.  The Rights Agreement, as amended hereby, shall remain in full force
and effect.

         9.  This Amendment shall be deemed to be a contract made under the laws
of the State of Delaware and for all purposes shall be governed by and construed
in accordance with the laws of such State applicable to contracts to be made and
performed entirely within such State.

         10.  This Amendment may be executed in any number of counterparts, and
each such counterpart shall for all purposes be deemed to be an original, and
all such counterparts shall together constitute but one and the same instrument.


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         IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
duly executed as of the day and year first above written.


                                    COHR INC.


                                    By:   /S/ LYNN REITNOUER
                                          -------------------------------
                                          Lynn Reitnouer
                                          Chairman


                                    CHASEMELLON SHAREHOLDER SERVICES LLC,
                                    as Rights Agent


                                    By:   /S/ JOSEPH CANNATA
                                          -------------------------------
                                          Joseph Cannata
                                          Assistant Vice President





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