SUPPLEMENTAL INDENTURE TO BE DELIVERED BY GUARANTEEING SUBSIDIARIES

                                                                   Exhibit 10.68

                     SUPPLEMENTAL INDENTURE TO BE DELIVERED
                          BY GUARANTEEING SUBSIDIARIES

         Supplemental Indenture (this "Supplemental Indenture"), dated as of
January 14, 2005, among L-3 Communications Corporation (or its permitted
successor), a Delaware corporation (the "Company"), each a direct or indirect
subsidiary of the Company signatory hereto (each, a "Guaranteeing Subsidiary",
and collectively, the "Guaranteeing Subsidiaries"), and The Bank of New York, as
trustee under the indenture referred to below (the "Trustee").

                               W I T N E S S E T H

               WHEREAS, the Company has heretofore executed and delivered to the
Trustee an indenture (the "Indenture"), dated as of November 12, 2004 providing
for the issuance of an unlimited amount of 5 7/8% Senior Subordinated Notes due
2015 (the "Notes");

               WHEREAS, the Indenture provides that under certain circumstances
the Guaranteeing Subsidiaries shall execute and deliver to the Trustee a
supplemental indenture pursuant to which the Guaranteeing Subsidiaries shall
unconditionally guarantee all of the Company's Obligations (as defined in the
Indenture) under the Notes and the Indenture on the terms and conditions set
forth herein (the "Subsidiary Guarantee"); and

               WHEREAS, pursuant to Section 9.01 of the Indenture, the Trustee
is authorized to execute and deliver this Supplemental Indenture.

               NOW THEREFORE, in consideration of the foregoing and for other
good and valuable consideration, the receipt of which is hereby acknowledged,
the Guaranteeing Subsidiaries and the Trustee mutually covenant and agree for
the equal and ratable benefit of the Holders of the Notes as follows:

               1. CAPITALIZED TERMS. Capitalized terms used herein without
definition shall have the meanings assigned to them in the Indenture.

               2. AGREEMENT TO GUARANTEE. Each Guaranteeing Subsidiary hereby
agrees as follows:

                  (a)   Such Guaranteeing Subsidiary, jointly and severally with
                        all other current and future guarantors of the Notes
                        (collectively, the "Guarantors" and each, a
                        "Guarantor"), unconditionally guarantees to each Holder
                        of a Note authenticated and delivered by the Trustee and
                        to the Trustee and its successors and assigns,
                        regardless of the validity and enforceability of the
                        Indenture, the Notes or the Obligations of the Company
                        under the Indenture or the Notes, that:

                        (i)   the principal of, premium, interest and Additional
                              Interest, if any, on the Notes will be promptly
                              paid in full when due, whether at maturity, by
                              acceleration, redemption or otherwise, and
                              interest on the overdue principal of, 




                              premium, interest and Additional Amounts, if any,
                              on the Notes, to the extent lawful, and all other
                              Obligations of the Company to the Holders or the
                              Trustee thereunder or under the Indenture will be
                              promptly paid in full, all in accordance with the
                              terms thereof; and

                        (ii)  in case of any extension of time for payment or
                              renewal of any Notes or any of such other
                              Obligations, that the same will be promptly paid
                              in full when due in accordance with the terms of
                              the extension or renewal, whether at stated
                              maturity, by acceleration or otherwise.

                  (b)   Notwithstanding the foregoing, in the event that this
                        Subsidiary Guarantee would constitute or result in a
                        violation of any applicable fraudulent conveyance or
                        similar law of any relevant jurisdiction, the liability
                        of such Guaranteeing Subsidiary under this Supplemental
                        Indenture and its Subsidiary Guarantee shall be reduced
                        to the maximum amount permissible under such fraudulent
                        conveyance or similar law.

               3. EXECUTION AND DELIVERY OF SUBSIDIARY GUARANTEES.

                  (a)   To evidence its Subsidiary Guarantee set forth in this
                        Supplemental Indenture, such Guaranteeing Subsidiary
                        hereby agrees that a notation of such Subsidiary
                        Guarantee substantially in the form of Exhibit F to the
                        Indenture shall be endorsed by an officer of such
                        Guaranteeing Subsidiary on each Note authenticated and
                        delivered by the Trustee after the date hereof.

                  (b)   Notwithstanding the foregoing, such Guaranteeing
                        Subsidiary hereby agrees that its Subsidiary Guarantee
                        set forth herein shall remain in full force and effect
                        notwithstanding any failure to endorse on each Note a
                        notation of such Subsidiary Guarantee.

                  (c)   If an Officer whose signature is on this Supplemental
                        Indenture or on the Subsidiary Guarantee no longer holds
                        that office at the time the Trustee authenticates the
                        Note on which a Subsidiary Guarantee is endorsed, the
                        Subsidiary Guarantee shall be valid nevertheless.

                  (d)   The delivery of any Note by the Trustee, after the
                        authentication thereof under the Indenture, shall
                        constitute due delivery of the Subsidiary Guarantee set
                        forth in this Supplemental Indenture on behalf of each
                        Guaranteeing Subsidiary.

                  (e)   Each Guaranteeing Subsidiary hereby agrees that its
                        Obligations hereunder shall be unconditional, regardless
                        of the validity, regularity or enforceability of the
                        Notes or the Indenture, the absence of any action to
                        enforce the same, any waiver or consent 




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                        by any Holder of the Notes with respect to any
                        provisions hereof or thereof, the recovery of any
                        judgment against the Company, any action to enforce the
                        same or any other circumstance which might otherwise
                        constitute a legal or equitable discharge or defense of
                        a guarantor.

                  (f)   Each Guaranteeing Subsidiary hereby waives diligence,
                        presentment, demand of payment, filing of claims with a
                        court in the event of insolvency or bankruptcy of the
                        Company, any right to require a proceeding first against
                        the Company, protest, notice and all demands whatsoever
                        and covenants that its Subsidiary Guarantee made
                        pursuant to this Supplemental Indenture will not be
                        discharged except by complete performance of the
                        Obligations contained in the Notes and the Indenture.

                  (g)   If any Holder or the Trustee is required by any court or
                        otherwise to return to the Company or any Guaranteeing
                        Subsidiary, or any custodian, Trustee, liquidator or
                        other similar official acting in relation to either the
                        Company or such Guaranteeing Subsidiary, any amount paid
                        by either to the Trustee or such Holder, the Subsidiary
                        Guarantee made pursuant to this Supplemental Indenture,
                        to the extent theretofore discharged, shall be
                        reinstated in full force and effect.

                  (h)   Each Guaranteeing Subsidiary agrees that it shall not be
                        entitled to any right of subrogation in relation to the
                        Holders in respect of any Obligations guaranteed hereby
                        until payment in full of all Obligations guaranteed
                        hereby. Each Guaranteeing Subsidiary further agrees
                        that, as between such Guaranteeing Subsidiary, on the
                        one hand, and the Holders and the Trustee, on the other
                        hand:

                        (i)   the maturity of the Obligations guaranteed hereby
                              may be accelerated as provided in Article 6 of the
                              Indenture for the purposes of the Subsidiary
                              Guarantee made pursuant to this Supplemental
                              Indenture, notwithstanding any stay, injunction or
                              other prohibition preventing such acceleration in
                              respect of the Obligations guaranteed hereby; and

                        (ii)  in the event of any declaration of acceleration of
                              such Obligations as provided in Article 6 of the
                              Indenture, such Obligations (whether or not due
                              and payable) shall forthwith become due and
                              payable by such Guaranteeing Subsidiary for the
                              purpose of the Subsidiary Guarantee made pursuant
                              to this Supplemental Indenture.

                  (i)   Each Guaranteeing Subsidiary shall have the right to
                        seek contribution from any other non-paying Guaranteeing
                        Subsidiary so long as the exercise of such right does
                        not impair the rights of 


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                        the Holders or the Trustee under the Subsidiary
                        Guarantee made pursuant to this Supplemental Indenture.

               4. GUARANTEEING SUBSIDIARY MAY CONSOLIDATE, ETC. ON CERTAIN 
                  TERMS.

                  (a)   Except as set forth in Articles 4 and 5 of the
                        Indenture, nothing contained in the Indenture, this
                        Supplemental Indenture or in the Notes shall prevent any
                        consolidation or merger of any Guaranteeing Subsidiary
                        with or into the Company or any other Guarantor or shall
                        prevent any transfer, sale or conveyance of the property
                        of any Guaranteeing Subsidiary as an entirety or
                        substantially as an entirety, to the Company or any
                        other Guarantor.

                  (b)   Except as set forth in Article 4 and 5 of the Indenture,
                        nothing contained in the Indenture, this Supplemental
                        Indenture or in the Notes shall prevent any
                        consolidation or merger of any Guaranteeing Subsidiary
                        with or into a corporation or