<PAGE>
                                                                  EXHIBIT 4.6(a)


                                 AMENDMENT NO. 7
                          DATED AS OF DECEMBER 12, 2006
                                    TO OFFER
                          DATED AS OF DECEMBER 3, 2001


                  Amendment No. 7 dated as of December 12, 2006 (the
"Amendment") between IDEX CORPORATION (the "Borrower") and CALYON NEW YORK
BRANCH (the "Lender") to the Offer dated as of December 3, 2001, as amended (the
"Offer"), for an uncommitted line of credit by the Lender in favor of the
Borrower.

                  WHEREAS, the Borrower has requested that the Lender amend the
offer by extending the Expiration Date.

                  NOW, THEREFORE, IT IS AGREED:

                  SECTION 1. Capitalized Terms. All terms used but not otherwise
defined herein shall have the meaning ascribed to them in the Offer.

                  SECTION 2. Amendments to Offer. Effective as of the date
hereof, the Offer is hereby amended as follows:

                  Clause (i) in the second paragraph of Section 1 of the Offer
is hereby amended to replace the phrase "December 12, 2006" with the phrase
"December 12, 2007."

                  SECTION 3. Conditions to Effectiveness. This Amendment shall
become effective as of the date first written above when the Lender shall have
received (i) counterparts of this Amendment executed by the Borrower and the
Lender, and (ii) such other documents, instruments or agreement as the Lender
shall reasonably request.

                  SECTION 4. Representations and Warranties. The Borrower hereby
represents and warrants that as of the date of effectiveness of this Amendment,
all representations and warranties set forth in the Offer are true and correct
as of such date, with each reference therein to the Offer meaning a reference to
the Offer as amended hereby.

                  SECTION 5. Reference to and Effect on Credit Documents.

                  (a) Upon the effectiveness hereof, on and after the date
hereof, each reference in the Credit Documents to "this Offer". "hereunder",
"hereof" or words of like import referring to the Offer and each reference in
instruments and documents delivered in connection therewith to "the Offer",
"thereunder", "thereof" or words of like import referring to the Offer shall
mean and be a reference to the Offer, as amended hereby.

<PAGE>
                                                                               2


                  (b) Except as expressly modified hereby, the terms and
provisions of the Offer and each Credit Document shall remain in full force and
effect and is hereby ratified in all respects by the Borrower.

                  (c) The execution, delivery and effectiveness of this
Amendment shall neither operate as a waiver of any rights, power or remedy of
the Lender under any of the Credit Documents nor constitute a waiver of any
provision of any of the Credit Documents.

                  SECTION 6. Governing Law. This Amendment shall be governed by
and construed in accordance with the laws of the State of New York, without
regard to its conflicts of laws principles.

                  SECTION 7. Execution in Counterparts.This Amendment may be
executed in any number of counterparts and by different parties hereto in
separate counterparts, each of which when so executed and delivered shall be
deemed to be an original and all of which taken together shall constitute but
one and the same agreement. Delivery of an executed counterpart of a signature
page to this Amendment by telecopier shall be effective as delivery of a
manually executed counterpart of this Amendment.

                  IN WITNESS WHEREOF, the parties hereto through their duly
authorized representatives have set their hand as of the date first written
above.


                               IDEX CORPORATION


                               By:
                                  -------------------------------------
                               Name:
                               Title:



                               CALYON NEW YORK BRANCH


                               By:
                                  -------------------------------------
                               Name: Greg Hennenfent
                               Title: Director


                               By:
                                   ------------------------------------
                               Name: Lee E. Greve
                               Title: Managing Director, Deputy Manager