<PAGE>

                                                                   EXHIBIT 10.21

PERSONAL AND CONFIDENTIAL
VIA OVERNIGHT MAIL

                                December 1, 2003

Mr. Dominic A. Romeo
10831 East Fanfol
Scottsdale, AZ 85259

Dear Dom:

      We are pleased to confirm our offer to you for the position of Vice
President - Chief Financial Officer for IDEX Corporation. The position is
situated at the Executive Office in Northbrook, Illinois. In this position, you
will report directly to Dennis Williams, IDEX Chief Executive Officer, Chairman,
and President.

      This letter supercedes the prior letter dated November 26, 2003 and
encompasses all parts of our final employment offer to you. The following terms
apply:

     -   Your annual base salary will be $315,000, payable on a biweekly basis
         at the rate of $12,115.38 per pay period. You will be eligible for a
         review of your salary with consideration for an increase on January 1,
         2005. While we hope that you have a long and mutually beneficial
         relationship with IDEX, your employment will not be for any fixed term
         or definite period and may be terminated at any time.

     -   You will be eligible for participation in our Management Incentive
         Compensation Plan (MICP), which provides an annual incentive earnings
         opportunity based on company and personal performance. You will be
         placed in Salary Range 26, which means your target level of extra
         compensation will be 65% of your annual base pay in effect at the
         beginning of the plan year. The actual payout under the plan could be
         more or less than the target level and will depend on the performance
         of IDEX and your individual performance. Enclosed is a copy of the IDEX
         MICP plan document.

<PAGE>

LETTER TO MR. DOMINIC A. ROMEO
December 1, 2003
Page Two

     -   You will be eligible for the full range of ChoiceComp benefits for IDEX
         employees at the Executive Office, including the IDEX Corporation
         Retirement Plan (defined benefit pension), IDEX Corporation
         Supplemental Executive Retirement Plan (benefits in excess of the IRS
         limits), 401(k) IDEX Savings Plan, medical and dental coverage,
         short-term and long-term disability coverage, life insurance, and
         enhanced one million-dollar business travel accident coverage. A
         ChoiceComp folder describing our flexible benefit plan is enclosed. You
         will be eligible for medical coverage on the first of the month
         following your employment date.

     -   As an IDEX officer, you are eligible to use a company-provided car
         under the IDEX Car Policy. Currently, you would be eligible for a BMW
         325i, Lexus 300, Buick Park Avenue, Chrysler 300 LX, or other
         similar-valued cars. You will be subject to taxable income for the
         personal use of this car under current IRS regulations. Doug Lennox,
         Treasurer, will assist you to place the order through Wheels, Inc.,
         which supplies our company cars.

     -   Subject to approval of our Board of Directors, we expect to award you
         an annual grant of stock options under the IDEX Corporation Stock
         Option Plan. This plan is designed to provide an incentive and reward
         to key employees who are in a position to make substantial
         contributions to the success of the company. Stock options are normally
         awarded to Officers at the Annual Shareholders' Meeting in March.

         The initial price at which the options are granted will be the fair
         market value on the day prior to the meeting at which the shares are
         approved (or the day before the date of issue, if they are issued at a
         later date). If and when the options are granted, we will notify you,
         provide you with a Stock Option Agreement, and ask that you sign the
         agreement and complete a beneficiary designation form.

     -   An initial, special stock option grant of 50,000 shares will be awarded
         to you immediately following your starting employment with IDEX. The
         initial price at which the options are granted will be the fair market
         value on the day immediately prior to the

<PAGE>

LETTER TO MR. DOMINIC A. ROMEO
December 1, 2003
Page Three

         effective date of the grant. Vesting will occur in five annual
         installments of twenty percent (20%) each, commencing on the first
         anniversary of the grant date. Accelerated vesting would occur in the
         event of change in control.

     -   As a special sign-on incentive, you will be awarded 20,000 shares of
         restricted stock with a five-year cliff-vesting requirement.
         Accelerated vesting would occur in the event of a change in control or
         termination of employment by the Company without cause. We will also
         provide a Restricted Stock Agreement for you to sign upon employment.

     -   As a replacement for your forfeited 2003 Honeywell annual bonus, we
         have agreed to pay you an amount equal to what you would have received
         had you remained employed at Honeywell through the payout date. You
         have indicated that this amount is approximated at $150,000. We will
         provide this payment as soon as practical following your employment
         date and the determination that the Honeywell bonus has actually been
         forfeited.

     -   Effective January 1, 2004, you will be eligible to participate in the
         IDEX Deferred Compensation Plan for Officers, which provides an
         alternative to defer income and subsequent earnings on that income
         until after retirement.

     -   You will be eligible for three (3) weeks of vacation during the
         vacation year from June 1 through May 31, and in each succeeding
         vacation year. In addition, we will accommodate vacation time you may
         require between now and May 31, 2004. Additionally, the IDEX Holiday
         schedule typically contains 14 paid holidays, including a shutdown
         period during the December holiday season.

     -   You will be eligible for the complete provisions of the IDEX moving
         policy, as it applies to current employees, including the third-party
         purchase of your home in Scottsdale, reimbursement of fees involved in
         the sale of your Scottsdale home and the purchase of a Chicago-area
         home, and payment of moving expenses. A copy of the moving policy is
         attached.

<PAGE>

LETTER TO MR. DOMINIC A. ROMEO
December 1, 2003
Page Four

         We are in agreement that you may delay the physical relocation of your
         home and family until mid-2004 to accommodate the completion of your
         children's current school year. To further support you through this
         transition, the Company will extend the temporary housing provisions of
         the moving policy and reimburse you for twice monthly return trips to
         your Scottsdale home through June 2004.

     -   As discussed with you, we expect that IDEX will continue to grow and
         prosper as an independent publicly-owned company. However, in the event
         of a "Change in Control," as defined in the 2001 Stock Option Plan for
         Officers of IDEX Corporation, that results in your termination from
         service within 24 months of the Change in Control, the Company would be
         obligated to pay your salary at the rate then in effect and your then
         current target MICP bonus for a minimum of 24 months following the date
         of termination. This payment would not be applicable in the event of
         your resignation.

     -   In other than a Change in Control event, should your employment with
         IDEX Corporation be terminated without cause ("cause" defined as
         willful misconduct or fraudulent behavior), you shall be entitled to 18
         months salary continuation at your then current base salary. This
         benefit would not be applicable in the event of your resignation.

     This offer of employment is subject to your satisfactory completion of a
drug and alcohol abuse-screening test. The test may be scheduled at a qualified
laboratory. The results should be communicated to me.

     At IDEX we have a strong standard of conduct and ethics policy, a copy of
which is enclosed. Immediately upon accepting employment, we ask that you sign a
statement indicating that you have read the policy and will abide by it.

     The company does require that all salaried employees agree to and sign a
Confidentiality and Invention Agreement. A copy is enclosed.

     Two copies of this offer letter are enclosed. Please indicate your
acceptance of this offer by signing on the line provided below and return a
signed copy to me by Tuesday, December 2, 2003.

<PAGE>

LETTER TO MR. DOMINIC A. ROMEO
December 1, 2003
Page Five

         Dom, we have discussed some of the critical challenges and
opportunities that our team faces. We are confident that your leadership skills
and experience can make a significant contribution to the success of IDEX, and
that this position can be a positive professional step for you.

                                            Sincerely,

                                            Kimberly Bors

     __________________________________        ________________
         Acceptance of Employment Offer              Date
               Dominic A. Romeo

KKB/jlk

c: D. K. Williams

Enclosures:

-        MICP Plan Document

-        2004 ChoiceComp Benefits Booklet

-        IDEX Defined Benefit Retirement Plan Summary

-        IDEX 401(k) Plan Summary

-        2004 Holiday Schedule

-        Moving Policy for Current Employees

-        Ethics policy

-        Ethics acknowledgement form

-        Confidentiality Agreement