Document:

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                                                                  EXECUTION COPY

                       DEBT REGISTRATION RIGHTS AGREEMENT

                                      among

                         L-3 COMMUNICATIONS CORPORATION

                              LEHMAN BROTHERS INC.
                           BANC OF AMERICA BRIDGE LLC
                         BANC OF AMERICA SECURITIES LLC
                     CREDIT SUISSE FIRST BOSTON CORPORATION
                CREDIT SUISSE FIRST BOSTON, CAYMAN ISLANDS BRANCH

        THE GUARANTORS listed on the signature pages hereto as Guarantors

                                       and

                          LEHMAN COMMERCIAL PAPER INC.

                            Dated as of March 8, 2002

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                       DEBT REGISTRATION RIGHTS AGREEMENT

         This DEBT REGISTRATION RIGHTS AGREEMENT (this "AGREEMENT") is made and
entered into as of March 8, 2002, among L-3 Communications Corporation, a
Delaware corporation (the "COMPANY"), Lehman Brothers Inc., Banc of America
Bridge LLC, Banc of America Securities LLC, Credit Suisse First Boston
Corporation (collectively, the "ARRANGERS"), Credit Suisse First Boston, Cayman
Islands Branch, the Guarantors listed on signature pages hereto (the
"GUARANTORS") and Lehman Commercial Paper Inc., as Administrative Agent
("ADMINISTRATIVE AGENT").

                                    RECITALS

         This Agreement is made pursuant to the Bridge Loan Agreement, dated as
of March 8, 2002 (the "BRIDGE LOAN AGREEMENT"), among the Company, the
Guarantors, the Lenders referred to therein (the "LENDERS"), the Arrangers and
the Administrative Agent. In order to induce the Lenders to enter into the
Bridge Loan Agreement, the Company and the Guarantors have agreed to provide the
registration rights set forth in this Agreement. The execution of this Agreement
is a condition to the effectiveness of the Bridge Loan Agreement.

                                    AGREEMENT

         The parties agree as follows:

     1. Definitions

         Capitalized terms used herein without definition have the meanings
assigned to them in the Bridge Loan Agreement. As used in this Agreement, the
following capitalized terms shall have the following meanings:

         ADDITIONAL AMOUNTS: See Section 3(b) hereof.
                                 ------------

         CLOSING DATE: The date of this Agreement.

         ESCROW AGENT: The Bank of New York, a New York banking corporation, in
its capacity as escrow agent pursuant the Escrow Agreement dated as of March 8,
2002, among the Company, Lehman Brothers Inc., Lehman Commercial Paper Inc.,
Banc of America Bridge LLC, Credit Suisse First Boston Corporation and The Bank
of New York, as escrow agent.

         EXCHANGE ACT: The Securities Exchange Act of 1934, as amended.

         EXCHANGE NOTE INDENTURE: The Indenture, dated as of March 8, 2002,
among the Company, the Guarantors, as guarantors and The Bank of New York, as
trustee, pursuant to which the Exchange Notes are issued, as the same may be
amended from time to time in accordance with the terms thereof.

         EXCHANGE NOTES: The Exchange Notes issued pursuant to the Exchange Note
Indenture in the form attached as Exhibit A to the Exchange Note Indenture.

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         LOANS: As defined in the Bridge Loan Agreement.

         NASD: National Association of Securities Dealers, Inc.

         PERSON: An individual, partnership, corporation, trust or
unincorporated organization, or a government or agency or political subdivision
thereof.

         PROSPECTUS: The prospectus included in any Registration Statement, as
amended or supplemented by any prospectus supplement with respect to the terms
of the offering of any portion of the Registrable Securities covered by such
Registration Statement and by all other amendments and supplements to the
prospectus, including post-effective amendments and all material incorporated by
reference in such prospectus.

         REGISTRABLE SECURITIES: All Exchange Notes; provided that an Exchange
Note ceases to be a Registrable Security when it is no longer a Transfer
Restricted Security.

         REGISTRANTS: The Company and the Guarantors.

         REGISTRATION DEFAULT: See Section 3(b) hereof.

         REGISTRATION EXPENSES: See Section 6 hereof.

         REGISTRATION STATEMENT: Any registration statement of the Registrants
which covers any of the Registrable Securities pursuant to the provisions of
this Agreement, including the Prospectus, amendments and supplements to such
Registration Statement, including post-effective amendments, all exhibits and
all material incorporated by reference in such Registration Statement.

         RULE 144: Rule 144 promulgated under the Securities Act.

         SEC: The Securities and Exchange Commission.

         SECURITIES ACT: The Securities Act of 1933, as amended.

         SHELF REGISTRATION: See Section 3(a) hereof.

         TIA: The Trust Indenture Act of 1939 (15 U.S.C. Section 77aaa-77bbbb)
as in effect on the date of the Exchange Note Indenture.

         TRANSFER RESTRICTED SECURITIES: The Registrable Securities beginning
upon original issuance thereof, and with respect to any particular Registrable
Security, until such Registrable Security is sold to the public or may be sold
or transferred pursuant to Rule 144 under the Securities Act without regard to
the volume limitations thereof.

         UNDERWRITTEN REGISTRATION or UNDERWRITTEN OFFERING: A registration in
which securities of the Company are sold to an underwriter for reoffering to the
public.

     2. Holders of Registrable Securities

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         A Person is deemed to be a holder of Registrable Securities whenever
such Person owns, beneficially or otherwise, Registrable Securities.

     3. Shelf Registration

         (a) Filing of Shelf Registration. The Registrants shall use its best
efforts to file a "shelf" registration statement on any appropriate form
pursuant to Rule 415 (or similar rule that may be adopted by the SEC) under the
Securities Act (a "SHELF REGISTRATION") on or prior to the one-year anniversary
of the Closing Date (the "FILING DATE") to permit resales of all of the
Registrable Securities. The Registrants agree to use all commercially reasonable
efforts to cause such Shelf Registration to become effective as promptly as
possible after the filing thereof, but in no event later than 120 days after the
Filing Date (the "EFFECTIVE DATE"), and thereafter to keep it continuously
effective for the period that will terminate upon the earlier of the date on
which (1) all the Registrable Securities covered by the Shelf Registration have
been sold pursuant to such Shelf Registration or are able to be sold to the
public without restriction pursuant to the volume limitation provisions of Rule
144 or any successor rule thereto or (2) no Registrable Securities or Loans
remain outstanding.

         (b) Additional Amounts. If (i) the Registration Statement has not been
declared effective by the SEC on or prior to the Effective Date or (ii) the
Registration Statement is filed and declared effective but shall thereafter
cease to be effective or fail to be usable for its intended purpose at any time
within the time period required for effectiveness in subsection (a) above
without being succeeded within 5 business days by a post-effective amendment to
the Registration Statement that cures such failure and that is itself
immediately declared effective or (iii) prior to or on the 45th or 60th day, as
the case may be, of any Suspension Period (as defined below), such suspension
has not been terminated (each such event referred to in clauses (i), (ii) and
(iii), a "REGISTRATION DEFAULT"), the Registrants jointly and severally agree to
pay Additional Amounts ("ADDITIONAL AMOUNTS") to each holder of Transfer
Restricted Securities with respect to the first 12-week period immediately
following the occurrence of such Registration Default, in the form of increased
interest of 25 basis points on the principal amount of Transfer Restricted
Securities. The amount of the Additional Amounts shall increase by 25 basis
points after the first 12-week period until all Registration Defaults have been
cured; provided that the Company shall in no event be required to pay Additional
Amounts for more than one Registration Default at any given time; provided,
further, that in no event shall the Additional Amounts accrue at a rate per year
exceeding 0.50% of the principal amount of the Exchange Notes. In addition,
unless and until the Company has cured all Registration Defaults, the holders of
Transfer Restricted Securities will have the right to "piggy-back" in the
registration of any debt or preferred equity securities (subject to customary
scale-back provisions) that are registered by the Company pursuant to a
registration statement filed subsequent to the time of the Registration Default
(other than on a Form S-4) unless all the Exchange Notes will be redeemed or
repaid from the proceeds of such securities. Following the cure of all
Registration Defaults relating to any particular Registrable Security, the
accrual of Additional Amounts with respect to such Registration Default will
cease.

         All obligations of the Registrants set forth in the preceding paragraph
that are outstanding with respect to any Transfer Restricted Security at the
time such security ceases to be a Transfer Restricted Security shall survive
until such time as all such obligations have been paid or

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satisfied in full, provided, however, that the Additional Amounts shall cease to
accrue on the day immediately prior to the date such Transfer Restricted
Securities cease to be Transfer Restricted Securities. Any holder of Registrable
Securities may notify the Exchange Note Indenture trustee (and any paying agent
under the Exchange Note Indenture) and the Administrative Agent under the Bridge
Loan Agreement immediately after the occurrence of each and every event which
pursuant to this Section 3(b) results in the accrual of Additional Amounts with
respect to such Registrable Securities.

     4. Hold-Back Agreements

         (a) Restrictions on Public Sale by Holder of Registrable Securities.
Each holder of Registrable Securities whose Registrable Securities are covered
by a Registration Statement filed pursuant to Section 3 hereof agrees, if
requested by the managing underwriters in an underwritten offering, not to
effect any public sale or distribution of securities of the Registrants of the
same class as the securities included in such Registration Statement, including
a sale pursuant to Rule 144 under the Securities Act (except as part of such
underwritten registration), during the 10-day period prior to, and during the
90-day period beginning on, the closing date of each underwritten offering made
pursuant to such Registration Statement, to the extent timely notified in
writing by the Registrants or the managing underwriters; provided, however, that
each holder of Registrable Securities shall be subject to the hold-back
restrictions of this Section 4(a) only once during the term of this Agreement.

         The foregoing provisions shall not apply to any holder of Registrable
Securities if such holder is prevented by applicable statute or regulation from
entering into any such agreement; provided, however, that any such holder shall
undertake, in its request to participate in any such underwritten offering, not
to effect any public sale or distribution of any Registrable Securities held by
such holder and covered by a Registration Statement commencing on the date of
sale of the Registrable Securities covered by such Registration Statement unless
it has provided 90 days prior written notice of such sale or distribution to the
underwriter or underwriters.

         (b) Restrictions on Sale of Securities by the Registrants and Others.
The Registrants agree not to effect any public or private offer, sale or
distribution of any of their debt securities or any class or series of their
capital stock having a preference in liquidation or with respect to dividends,
including a sale pursuant to Regulation D under the Securities Act, during the
10-day period prior to, and during the 90-day period beginning with, the
effectiveness of a Registration Statement filed under Section 3 hereof to the
extent timely notified in writing by a holder of Registrable Securities or the
managing underwriters in an underwritten offering.

     5. Registration Procedures

         In connection with the Registrants' Shelf Registration obligations set
forth in Section 3 hereof, each of the Registrants will use all reasonable
efforts to effect such registration to permit the sale of such Registrable
Securities in accordance with the intended method or methods of distribution
thereof, and pursuant thereto the Registrants will, as expeditiously as
possible:

         (a) prepare and file with the SEC, within the time period provided in
Section 3 hereof, a Registration Statement or Registration Statements relating
to the Shelf Registration on

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any appropriate form under the Securities Act, which form shall be available for
the sale of the Registrable Securities in accordance with the intended method or
methods of distribution thereof and shall include or incorporate by reference
(i) all financial statements (including, if applicable, financial statements of
any Person which shall have guaranteed any indebtedness of the Registrants)
required by the SEC to be filed therewith and (ii) if the sale is by means of an
underwritten offering, any other information that the managing underwriter(s)
may reasonably request to have included therein, including, without limitation:
(A) information relating to the "Plan of Distribution" of the Transfer
Restricted Securities, (B) information with respect to the principal amount of
Exchange Notes being sold to such underwriter(s), (C) the purchase price being
paid therefor and (D) any other terms of the offering of the Transfer Restricted
Securities to be sold in such offering, cooperate and assist in any filings
required to be made with the NASD and in the performance of any due diligence
investigation by any underwriter (including any "qualified independent
underwriter") that is required to be retained in accordance with the rules and
regulations of the NASD, and use all reasonable efforts to cause such
Registration Statement to become effective; provided that before filing a
Registration Statement or any amendments or supplements thereto, the Registrants
will furnish to the holders of the Registrable Securities covered by such
Registration Statement and the underwriters, if any, copies of all such
documents proposed to be filed, which documents will be subject to the review by
such holders and underwriters, and the Registrants will not file any
Registration Statement or any amendments or supplements thereto to which the
holders of a majority in aggregate principal amount of such Registrable
Securities or such managing underwriters, if any, shall reasonably object within
14 days;

         (b) prepare and file with the SEC such amendments and post-effective
amendments to the Registration Statement as may be necessary to keep the
Registration Statement effective for the applicable period, or such shorter
period as will terminate when all Registrable Securities covered by such
Registration Statement have been sold or are no longer Transfer Restricted
Securities; cause the Prospectus to be supplemented by any required Prospectus
supplement, and as so supplemented to be filed pursuant to Rule 424 under the
Securities Act; comply with the applicable provisions of Rules 424 and 430A
under the Securities Act in a timely manner; and comply with the provisions of
the Securities Act with respect to the disposition of all Registrable Securities
covered by such Registration Statement during the applicable period in
accordance with the intended method or methods of distribution by the sellers
thereof set forth in such Registration Statement or supplement to the
Prospectus. Notwithstanding the foregoing, the Registrants may suspend the
effectiveness of the Registration Statement by written notice to the holders of
Registrable Securities for a period not to exceed an aggregate of 45 days in any
90-day period (each such period, a "Suspension Period") if:

               (i) an event occurs and is continuing as a result of which the
               Registration Statement would, in the Registrants' reasonable
               judgment, contain an untrue statement of a material fact or omit
               to state a material fact required to be stated therein or
               necessary to make the statements therein not misleading; and

               (ii) the Registrants reasonably determine that the disclosure of
               such event at such time would have a material adverse effect on
               the business of the Registrants (and their subsidiaries, if any,
               taken as a whole);

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provided, however, that in the event the disclosure relates to a previously
undisclosed proposed or pending material business transaction, the disclosure of
which would impede the Registrants' ability to consummate such transaction, the
Registrants may extend a Suspension Period from 45 days to 60 days; provided,
however, that Suspension Periods shall not exceed an aggregate of 90 days in any
360-day period;

         (c) notify the selling holders of Registrable Securities and the
managing underwriters, if any, promptly, and (if requested by any such Person)
confirm such advice in writing, (1) when the Prospectus or any Prospectus
supplement or post-effective amendment has been filed, and, with respect to the
Registration Statement or any post-effective amendment, when the same has become
effective, (2) of any request by the SEC for amendments or supplements to the
Registration Statement or the Prospectus or for additional information, (3) of
the issuance by the SEC of any stop order suspending the effectiveness of the
Registration Statement or the initiation of any proceedings for that purpose,
(4) if at any time the representations and warranties of the Registrants
contemplated by paragraph (o) below cease to be true and correct, (5) of the
receipt by the Registrants of any notification with respect to the suspension of
the qualification of the Registrable Securities for sale in any jurisdiction or
the initiation or threatening of any proceeding for such purpose and (6) of the
happening of any event or the existence of any fact which makes any statement
made in the Registration Statement, the Prospectus or any document incorporated
therein by reference untrue or which requires the making of any changes in the
Registration Statement, the Prospectus or any document incorporated therein by
reference in order to make the statements therein not misleading. If at any time
the Commission shall issue any stop order suspending the effectiveness of the
Registration Statement, or any state securities commission or other regulatory
authority shall issue an order suspending the qualification or exemption from
qualification of the Transfer Restricted Securities under state securities or
Blue Sky laws, the Registrants shall use their reasonable efforts to obtain the
withdrawal or lifting of such order at the earliest possible time;

         (d) make every reasonable effort to obtain the withdrawal of any order
suspending the effectiveness of the Registration Statement at the earliest
possible moment;

         (e) if reasonably requested by the managing underwriter or underwriters
or a holder of Registrable Securities being sold in connection with an
underwritten offering, promptly incorporate in a Prospectus supplement or
post-effective amendment such information as the managing underwriters or the
holders of a majority in aggregate principal amount of the Registrable
Securities being sold agree should be included therein relating to the plan of
distribution with respect to such Registrable Securities, including, without
limitation, information with respect to the principal amount of Registrable
Securities being sold to such underwriters, the purchase price being paid
therefor by such underwriters and any other terms of the underwritten (or best
efforts underwritten) offering of the Registrable Securities to be sold in such
offering; and make all required filings of such Prospectus supplement or
post-effective amendment promptly following notification of the matters to be
incorporated in such Prospectus supplement or post-effective amendment;

         (f) furnish to each selling holder of Registrable Securities and each
managing underwriter, if any, without charge, if requested, at least one signed
copy of the Registration Statement and any post-effective amendment thereto,
including financial statements and

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schedules, all documents incorporated therein by reference and all exhibits
(including those incorporated by reference);

         (g) deliver to each selling holder of Registrable Securities and the
underwriters, if any, without charge, if requested, as many copies of the
Prospectus (including each preliminary prospectus) and any amendment or
supplement thereto as such Persons may reasonably request; the Registrants
consent to the use of the Prospectus or any amendment or supplement thereto by
each of the selling holders of Registrable Securities and the underwriters, if
any, in connection with the offering and sale of the Registrable Securities
covered by the Prospectus or any amendment or supplement thereto;

         (h) prior to any public offering of Registrable Securities, register or
qualify or cooperate with the selling holders of Registrable Securities, the
underwriters, if any, and their respective counsel in connection with the
registration or qualification of such Registrable Securities for offer and sale
under the securities or blue sky laws of such jurisdictions as any such seller
or underwriter reasonably requests in writing and do any and all other acts or
things necessary or advisable to enable the disposition in such jurisdictions of
such Registrable Securities; provided that the Registrants will not be required
to qualify generally to do business in any jurisdiction where it is not then so
qualified or to take any action which would subject it to general service of
process in any such jurisdiction where it is not then so subject or would
subject the Registrants to taxation in any jurisdiction if they are not now so
subject;

         (i) cooperate with the selling holders of Registrable Securities and
the managing underwriters, if any, to facilitate the timely preparation and
delivery of certificates representing such Registrable Securities to be sold and
not bearing any restrictive legends (unless required by applicable securities
laws); and enable such Registrable Securities to be in such denominations and
registered in such names as such managing underwriters may request at least two
business days prior to any sale of such Registrable Securities to the
underwriters;

         (j) use all reasonable efforts to cause the Registrable Securities
covered by the applicable Registration Statement to be registered with or
approved by such other governmental agencies or authorities as may be necessary
to enable the seller or sellers thereof or the underwriters, if any, to
consummate the disposition of such Registrable Securities;

         (k) subject to Section 5(b) hereof, upon the occurrence of any event
contemplated by paragraph (c)(6) above, use all reasonable efforts to prepare a
supplement or post-effective amendment to the related Registration Statement or
the related Prospectus or any document incorporated therein by reference or file
any other required document so that, as thereafter delivered to the holders of
the Registrable Securities, the Prospectus will not contain an untrue statement
of a material fact or omit to state any material fact required to be stated
therein or necessary to make the statements therein not misleading;

         (l) use their reasonable best efforts to cause all Registrable
Securities covered by a Registration Statement to be listed on each securities
exchange on which similar securities issued by the Registrants are then listed;

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         (m) cause the Registrable Securities covered by a Registration
Statement to be rated with such rating agencies as the holders of a majority in
aggregate principal amount of such Registrable Securities or the managing
underwriters, if any, may designate;

         (n) not later than the effective date of the Shelf Registration,
provide a CUSIP number for all Registrable Securities and provide the Exchange
Note Indenture trustee or transfer agent with printed certificates for the
Registrable Securities which are in a form eligible for deposit with The
Depository Trust Company;

         (o) enter into such agreements (including an underwriting agreement)
and take all such other actions in connection therewith in order to expedite or
facilitate the disposition of such Registrable Securities and in such
connection, whether or not an underwriting agreement is entered into and whether
or not the registration is an underwritten registration (1) make such
representations and warranties to the holders of such Registrable Securities and
the underwriters, if any, in form, substance and scope as are customarily made
by issuers to underwriters in primary underwritten offerings; (2) obtain
opinions of counsel to the Registrants and updates thereof (which counsel and
opinions (in form, scope and substance) shall be reasonably satisfactory to the
managing underwriters, if any, and the holders of a majority in principal amount
of such Registrable Securities) addressed to each selling holder and the
underwriters, if any, covering the matters customarily covered in opinions
requested in underwritten offerings and such other matters as may be reasonably
requested by such holders and underwriters; (3) obtain "comfort" letters and
updates thereof from the Registrants' independent certified public accountants
addressed to such holders and underwriters, if any, such letters to be in
customary form and covering matters of the type customarily covered in "comfort"
letters by underwriters in connection with primary underwritten offerings; (4)
if an underwriting agreement is entered into, the same shall set forth in full
the indemnification provisions and procedures of Section 7 hereof with respect
to all parties to be indemnified pursuant to Section 7; and (5) deliver such
documents and certificates as may be requested by the holders of a majority of
the Registrable Securities being sold and the managing underwriters, if any, to
evidence compliance with clause (k) above and with any customary conditions
contained in the underwriting agreement or other agreement entered into by the
Registrants. The above shall be done at each closing under such underwriting or
similar agreement or as and to the extent required thereunder;

         (p) make available at reasonable times for inspection by one or more
representatives of the selling holders of Registrable Securities, designated in
writing by a majority of such selling holders, any underwriter participating in
any distribution of such Registrable Securities pursuant to a Shelf
Registration, and any attorney or accountant retained by such selling holders or
any of the underwriter(s), all financial and other records, pertinent corporate
documents and properties of the Registrants as shall be reasonably necessary to
enable them to exercise any applicable due diligence responsibilities, and cause
the Registrant's officers, directors, managers and employees to supply all
information reasonably requested by any such representative or representatives
of the selling holders, underwriter, attorney or accountant in connection with
the Shelf Registration after the filing thereof and before its effectiveness;
provided, however, that any information designated by the Registrants as
confidential at the time of delivery of such information shall be kept
confidential by the recipient thereof; provided further, that in no event shall
the Registrants be required to furnish any material nonpublic information
pursuant to this subsection (p).

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         (q) otherwise use their best efforts to comply with all applicable
rules and regulations of the SEC;

         (r) cause the Exchange Note Indenture to be qualified under the TIA,
provide an indenture trustee for each of the Registrable Securities not later
than the effective date of the Shelf Registration, and in connection therewith,
cooperate with the trustee under the Exchange Note Indenture and the holders of
the Exchange Notes to effect such changes to the Exchange Note Indenture as may
be required for the Exchange Note Indenture to be so qualified in accordance
with the terms of the TIA and execute, and use all reasonable efforts to cause
such trustee to execute, all documents as may be required to effect such changes
and all other forms and documents required to be filed with the SEC to enable
the Exchange Note Indenture to be so qualified in a timely manner; and

         (s) if reasonably requested by the underwriters, make appropriate
officers of the Registrants reasonably available to the underwriters for
meetings with prospective purchasers of the Registrable Securities and prepare
and present to potential investors "roadshow" material in a manner consistent
with other new issuances of high yield debt securities.

         The Registrants may require each seller of Registrable Securities as to
which any registration is being effected to furnish to the Registrants such
information regarding the distribution of such securities as the Registrants may
from time to time reasonably request in writing.

         Each holder of Registrable Securities agrees by acceptance of such
Registrable Securities that, upon receipt of any notice from the Registrants of
the happening of any event of the kind contemplated by Section 5(c)(6) hereof,
such holder will and will use its reasonable best efforts to cause any
underwriter to forthwith discontinue disposition of Registrable Securities until
such holder's receipt of the copies of the supplemented or amended Prospectus
contemplated by Section 5(k) hereof, or until such holder is advised in writing
(the "Advice") by the Registrants that the use of such Prospectus may be
resumed, and has received copies of any additional or supplemental filings which
are incorporated by reference in such Prospectus, and, if so directed by the
Registrants, such holder will deliver to the Registrants (at the Registrants'
expense) all copies, other than permanent file copies then in such holder's
possession, of such Prospectus covering such Registrable Securities current at
the time of receipt of such notice. In the event the Registrants shall give any
such notice, the time periods regarding the maintenance of the Shelf
Registration and the filing and maintenance of the Shelf Registration in Section
3 hereof shall be extended by the number of days during the period from and
including the date of the giving of such notice pursuant to Section 5(c)(6)
hereof to and including the date when each seller of Registrable Securities
covered by such Registration Statement shall have received the copies of the
supplemented or amended Prospectus contemplated by Section 5(k) hereof or the
Advice.

     6. Registration Expenses

         (a) All expenses incident to the Registrants' performance of or
compliance with this Agreement, including without limitation all (i)
registration and filing fees, fees and expenses associated with filings required
to be made with the NASD (including, if applicable, the fees and expenses of any
"qualified independent underwriter" and their counsel as may be required by the

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rules and regulations of the NASD), (ii) fees and expenses of compliance with
securities or blue sky laws (including fees and disbursements of counsel for the
underwriters or selling holders in connection with blue sky qualifications of
the Registrable Securities and determination of their eligibility for investment
under the laws of such jurisdictions as the managing underwriters or holders of
a majority in aggregate principal amount of the Registrable Securities being
sold may designate), (iii) printing expenses (including expenses of printing
certificates for the Registrable Securities in a form eligible for deposit with
The Depository Trust Company and of printing prospectuses), messenger, telephone
and delivery expenses, (iv) fees and disbursements of counsel for the
Registrants and for the sellers of the Registrable Securities (subject to the
provisions of Section 6(b) hereof), of all independent certified public
accountants (including the expenses of any special audit and "comfort" letters
required by or incident to such performance), (v) the cost of securities acts
liability insurance if the Registrants so desires, (vi) "roadshow" travel and
other expenses incurred in connection with the marketing and sale of the
Registrable Securities, (vii) fees and expenses in connection with the rating of
the Registrable Securities by rating agencies, if any, and (viii) fees and
expenses of other Persons retained by the Registrants (all such expenses being
herein called "REGISTRATION EXPENSES") will be borne by the Registrants,
regardless of whether the Registration Statement becomes effective. The
Registrants, in any event, will pay their own internal expenses (including,
without limitation, all salaries and expenses of their officers and employees
performing legal or accounting duties), the expense of any annual audit, the
fees and expenses incurred in connection with the listing of the securities to
be registered on each securities exchange on which similar securities issued by
the Registrants are then listed, rating agency fees and the fees and expenses of
any Person, including special experts, retained by the Registrants.

         (b) In connection with the Shelf Registration hereunder, the
Registrants will reimburse the selling holders of Registrable Securities being
registered in such registration for the reasonable fees and disbursements not to
exceed the amount of $50,000 of not more than one law firm, which shall be
Latham & Watkins, or such other counsel as may be chosen by the selling holders
of a majority in principal amount of such Registrable Securities.

     7. Indemnification

         (a) Indemnification by the Registrants. The Registrants jointly and
severally agree to indemnify and hold harmless, to the full extent permitted by
law, each holder of Registrable Securities, their officers, directors and
employees and each Person who controls such holder (within the meaning of the
Securities Act) (the "INDEMNIFIED PARTIES") against all losses, claims, damages,
liabilities and expenses incurred by such party in connection with any actual or
threatened action arising out of or based upon any untrue or alleged untrue
statement of a material fact contained in any Registration Statement or
Prospectus or any omission or alleged omission to state therein a material fact
required to be stated therein or necessary to make the statements therein not
misleading, and the Registrants agree to reimburse such Indemnified Parties for
any legal or other expenses reasonably incurred by them in connection with
investigating or defending any such loss or action or proceeding in respect
thereof, except insofar as the same arise out of or are based upon any such
untrue statement or omission made in reliance on and in conformity with any
information furnished in writing to the Registrants by such holder or its
counsel expressly for use therein or out of the failure by the Indemnified
Parties to furnish to any purchaser of Registrable Securities of the Prospectus
and any

                                       11
<PAGE>

supplement or amendment thereto in the form provided to such Indemnified Parties
by the Registrants. The Registrants shall also indemnify underwriters, their
officers and directors and each Person who controls such Persons (within the
meaning of the Securities Act) to the same extent as provided above with respect
to the indemnification of the Indemnified Parties, if requested.

         (b) Indemnification by Holder of Registrable Securities. In connection
with the Shelf Registration, each holder of Registrable Securities will furnish
to the Registrants in writing such information and affidavits as the Registrants
reasonably request for use in connection with any Registration Statement or
Prospectus and agrees to indemnify and hold harmless, to the full extent
permitted by law, the Registrants, their directors and officers and each Person
who controls the Registrants (within the meaning of the Securities Act) against
any losses, claims, damages, liabilities and expenses resulting from any untrue
statement of a material fact contained in any Registration Statement or
Prospectus or any omission of a material fact required to be stated in the
Registration Statement or Prospectus or necessary to make the statements
therein, in light of the circumstances under which they were made, not
misleading, to the extent, but only to the extent, that such untrue statement or
omission relates to such holder and is made in reliance on and in conformity
with any information or affidavit furnished in writing by such holder to the
Registrants specifically for inclusion in such Registration Statement or
Prospectus. In no event shall the liability of any selling holder of Registrable
Securities hereunder be greater in amount than the dollar amount of the proceeds
received by such holder upon the sale of the Registrable Securities giving rise
to such indemnification obligation. The Registrants shall be entitled to receive
indemnities from underwriters, selling brokers, dealer managers and similar
securities industry professionals participating in the distribution of such
Registrable Securities to the same extent above with respect to information or
affidavit furnished writing by such Persons as provided specifically for any
Prospectus or Registration Statement.

         (c) Conduct of Indemnification Proceedings. Any Person entitled to
indemnification hereunder will (i) give prompt written notice to the Registrants
or holder of Registrable Securities, as the case may be (in either case, as
applicable, an "INDEMNIFYING PARTY"), of any claim with respect to which it
seeks indemnification and (ii) permit such Indemnifying Party to assume the
defense of such claim with counsel reasonably satisfactory to such Person;
provided, however, that any Person entitled to indemnification hereunder shall
have the right to employ separate counsel and to participate in the defense of
such claim, but the fees and expenses of such counsel shall be at the expense of
such Person unless (a) the Indemnifying Party has agreed to pay such fees or
expenses, (b) the Indemnifying Party has failed to assume the defense of such
claim or (c) if holders of 50% in aggregate principal amount of Registrable
Securities shall have reasonably concluded that there may be one or more legal
defenses available to them and their respective officers, employees and
controlling persons that are different from or additional to those available to
the Registrants and any of their respective directors, officers, employees and
controlling persons. If such defense is not assumed by the Indemnifying Party,
the Indemnifying Party will not be subject to any liability for any settlement
made without its prior written consent (but such consent will not be
unreasonably withheld). No Indemnifying Party will consent to entry of any
judgment or enter into any settlement without the consent of the Indemnified
Party which does not include as an unconditional term thereof the giving by the
claimant or plaintiff to such Indemnified Party a release from all liability in
respect to such claim or litigation.

                                       12
<PAGE>

         (d) Contribution. If for any reason the indemnification provided for in
the preceding paragraphs (a) and (b) is unavailable to a Person entitled to
indemnification or is insufficient to hold it harmless as contemplated by the
preceding paragraphs (a) and (b), then the Indemnifying Party shall contribute
to the amount paid or payable by such Person as a result of such loss, claim,
damage or liability in such proportion as is appropriate to reflect the relative
fault of such Person and the Indemnifying Party, as well as any other relevant
equitable considerations, provided that no holder of Registrable Securities
shall be required to contribute an amount greater than the dollar amount of the
proceeds received by such holder of Registrable Securities with respect to the
sale of any securities. The relative fault shall be determined by reference to,
among other things, whether the untrue or alleged untrue statement of a material
fact or the omission or alleged omission to state a material fact relates to
information supplied by the Indemnifying Party or the Indemnified Party and the
parties' relative intent, knowledge, access to information and opportunity to
correct or prevent such untrue statement or omission. The parties hereto agree
that it would not be just and equitable if contributions pursuant to this
paragraph were to be determined by pro rata allocation or by any other method of
allocation which does not take into account the equitable considerations
referred to in the first sentence of this paragraph. No Person guilty of
fraudulent misrepresentation (within the meaning of Section 11(f) of the
Securities Act) shall be entitled to contribution from any Person who was not
guilty of such fraudulent misrepresentation.

8. Rule 144. The Registrants covenant that they will file the reports required
to be filed by them under the Securities Act and the Exchange Act and the rules
and regulations adopted by the SEC thereunder (or, if any of them is not
required to file such reports, the applicable party will, upon the written
request of any holder of Registrable Securities made after the two year
anniversary of the making of the Loans, make publicly available other
information so long as necessary to permit sales pursuant to Rule 144 under the
Securities Act), and they will take such further action as any holder of
Registrable Securities may reasonably request, all to the extent required from
time to time to enable such holder to sell Registrable Securities without
registration under the Securities Act within the limitation of the exemptions
provided by (a) Rule 144 under the Securities Act, as such Rule may be amended
from time to time, or (b) any similar rule or regulation hereafter adopted by
the SEC. Upon the written request of any holder of Registrable Securities, the
Registrants will deliver to such holder a written statement as to whether they
have complied with such information and filing requirements.

9. CUSIP Number. Prior to the one-year anniversary of the Closing Date and the
issuance of the Exchange Notes, the Company agrees to obtain a CUSIP number for
the Exchange Notes, and to notify the Escrow Agent of the same for addition to
the Exchange Notes.

10. Selection of Underwriters. The holders of Transfer Restricted Securities
covered by the Shelf Registration who desire to do so may sell such Transfer
Restricted Securities in an underwritten offering. In any such underwritten
offering, the investment banker or investment bankers and manager or managers
that will administer the offering will be selected by a majority of holders
whose Transfer Restricted Securities are included in such offering; provided,
however, that such investment bankers and managers must be reasonably
satisfactory to the Company.

11.      Miscellaneous

                                       13
<PAGE>

         (a) Remedies. Each holder of Registrable Securities in addition to
being entitled to exercise all rights provided herein, in the Exchange Note
Indenture or granted by law, including recovery of damages, in connection with
the breach by the Registrants of their obligations to register the Registrable
Securities will be entitled to specific performance of its rights under this
Agreement. The Registrants agree that monetary damages (including the Additional
Amounts contemplated hereby) would not be adequate compensation for any loss
incurred by reason of a breach by any of them of the provisions of this
Agreement and each agrees to waive the defense in any action for specific
performance that a remedy at law would be adequate.

         (b) No Inconsistent Agreements. The Registrants will not on or after
the date of this Agreement enter into any Agreement, with respect to their
securities which (i) interferes with the rights granted to the holders of
Transfer Restricted Securities in this Agreement, (ii) grants to the holders of
any securities issued or to be issued by the Company the right to participate in
any registration of Registrable Securities pursuant to this Agreement or (iii)
otherwise conflicts with the provisions hereof. The rights granted to the
holders of Registrable Securities hereunder do not in any way conflict with and
are not inconsistent with the rights granted to the holders of the Registrants'
respective securities under any other agreements.

         (c) Amendments and Waivers. The provisions of this Agreement, including
the provisions of this sentence, may not be amended, modified or supplemented,
and waivers or consents to departures from the provisions of this Agreement may
not be given unless the Registrants have obtained the written consent of holders
of at least a majority of the principal amount of (x) the outstanding
Registrable Securities and (y) the outstanding Loans (excluding Registrable
Securities held by the Company, the Guarantors or one of their respective
affiliates); provided that provisions hereunder relating to Additional Amounts
and the payment thereof may not be amended, modified or supplemented, and
waivers or consents to departures from such provisions may not be given unless
the Registrants have obtained the written consent of holders of at least 66-2/3%
of the principal amount of (x) the outstanding Registrable Securities and (y)
the outstanding Loans (excluding Registrable Securities held by the Company, the
Guarantors or one of their respective affiliates).

         (d) Notices. All notices and other communications provided for or
permitted hereunder shall be made in writing by hand-delivery, registered
first-class mail, facsimile or air courier guaranteeing overnight delivery:

                  (i) if to a holder of Registrable Securities, at the most
current address given by such holder to the Registrants in accordance with the
provisions of this Section 9(d), which address initially is, with respect to the
Administrative Agent to it at the address set forth in the Bridge Loan
Agreement, with a copy to:

                           Latham & Watkins
                           885 Third Avenue, Suite 1000
                           New York, New York 10022
                           Attn: Kirk A. Davenport II
                           Facsimile No.: (212) 751-4864

                                       14
<PAGE>

                  (ii) if to the Registrants, initially to them at the address
set forth in the Bridge Loan Agreement and thereafter at such other address,
notice of which is given in accordance with the provisions of this Section 9(d),
with copies to:

                           Simpson Thacher & Bartlett
                           425 Lexington Avenue
                           New York, NY, 10017
                           Attention: Vincent Pagano Jr.
                           Facsimile No.: 212-455-2502

         All such notices and communications shall be deemed to have been duly
given at the time delivered by hand, if personally delivered; five business days
after being deposited in the mail, postage prepaid, if mailed; when answered
back, if delivered by facsimile; and on the next business day if timely
delivered to an air courier guaranteeing overnight delivery.

         Copies of all such notices, demands or other communications shall be
concurrently delivered by the Person giving the same to the trustee under the
Exchange Note Indenture at the address specified in the Exchange Note Indenture.

         (e) Successors and Assigns. This Agreement shall inure to the benefit
of and be binding upon the successors and assigns of each of the parties hereto,
including without limitation and without the need for an express assignment, all
subsequent holders of Registrable Securities or Loans.

         (f) Counterparts. This Agreement may be executed in any number of
counterparts and by the parties hereto in separate counterparts, each of which
when so executed shall be deemed to be an original and all of which taken
together shall constitute one and the same agreement.

         (g) Headings. The headings in this Agreement are for convenience of
reference only and shall not limit or otherwise affect the meaning hereof.

         (h) New York Law; Submission to Jurisdiction; Waiver of Jury Trial.
THIS AGREEMENT SHALL BE CONSTRUED IN ACCORDANCE WITH AND GOVERNED BY THE LAWS OF
THE STATE OF NEW YORK. EACH PARTY HERETO HEREBY SUBMITS TO THE NONEXCLUSIVE
JURISDICTION OF THE UNITED STATES DISTRICT COURT FOR THE SOUTHERN DISTRICT OF
NEW YORK AND OF ANY NEW YORK STATE COURT SITTING IN NEW YORK CITY FOR PURPOSES
OF ALL LEGAL PROCEEDINGS ARISING OUT OF OR RELATING TO THIS AGREEMENT OR THE
TRANSACTIONS CONTEMPLATED HEREBY. EACH PARTY HERETO IRREVOCABLY WAIVES, TO THE
FULLEST EXTENT PERMITTED BY LAW, ANY OBJECTION WHICH IT MAY NOW OR HEREAFTER
HAVE TO THE LAYING OF THE VENUE OF ANY SUCH PROCEEDING BROUGHT IN SUCH A COURT
AND ANY CLAIM THAT ANY SUCH PROCEEDING BROUGHT IN SUCH A COURT HAS BEEN BROUGHT
IN AN INCONVENIENT FORUM. EACH PARTY HERETO IRREVOCABLY WAIVES ANY AND ALL RIGHT
TO TRIAL BY

                                       15
<PAGE>

JURY IN ANY LEGAL PROCEEDING ARISING OUT OF OR RELATING TO THIS AGREEMENT OR THE
TRANSACTIONS CONTEMPLATED HEREBY.

         (i) Severability. In the event that any one or more of the provisions
contained herein, or the application thereof in any circumstance, is held
invalid, illegal or unenforceable in any jurisdiction, the validity, legality
and enforceability of any such provision in such Jurisdiction in every other
respect and of the remaining provisions contained herein shall not be affected
or impaired thereby.

         (j) Entire Agreement. This Agreement is intended by the parties as a
final expression of their agreement with respect to the subject matter contained
herein and intended to be a complete and exclusive statement of the agreement
and understanding of the parties hereto in respect of the subject matter
contained herein. There are no restrictions, promises, warranties or
undertakings, other than those set forth or referred to herein with respect to
the registration rights granted by the Registrants with respect to the
securities sold pursuant to the Bridge Loan Agreement. This Agreement supersedes
all prior agreements and understandings between the parties with respect to such
subject matter.

                                       16
<PAGE>

         IN WITNESS WHEREOF, the parties have executed this Agreement as of the
date first written above.

                           L-3 COMMUNICATIONS CORPORATION,
                                    as the Company

                           By:_______________________________
                                Name:  Christopher C. Cambria
                                Title: Senior Vice President, Secretary and
                                       General Counsel

COLEMAN RESEARCH CORPORATION
EER SYSTEMS, INC.
ELECTRODYNAMICS, INC.
HENSCHEL, INC.
HYGIENETICS ENVIRONMENTAL SERVICES, INC.
INTERSTATE ELECTRONICS CORPORATION
L-3 COMMUNICATIONS ANALYTICS CORPORATION
L-3 COMMUNICATIONS AYDIN CORPORATION
L-3 COMMUNICATIONS DBS MICROWAVE, INC.
L-3 COMMUNICATIONS ESSCO, INC.
L-3 COMMUNICATIONS ILEX SYSTEMS, INC.
L-3 COMMUNICATIONS SPD TECHNOLOGIES, INC.
L-3 COMMUNICATIONS STORM CONTROL SYSTEMS, INC.
KDI PRECISION PRODUCTS, INC.
MICRODYNE CORPORATION
MPRI, INC.
PAC ORD, INC.
POWER PARAGON, INC.
SOUTHERN CALIFORNIA MICROWAVE, INC.
SPD HOLDINGS, INC.
SPD ELECTRICAL SYSTEMS, INC.
SPD SWITCHGEAR, INC.
L-3 COMMUNICATIONS AIS GP CORPORATION
L-3 COMMUNICATIONS INVESTMENTS, INC.

By:  ______________________________________
      Name:  Christopher C. Cambria
      Title: Vice President

                                       17
<PAGE>

L-3 COMMUNICATIONS INTEGRATED SYSTEMS L.P.

By:   L-3 Communications AIS GP Corporation,
      as general partner

      By:  ______________________________________
      Name:
      Title: Authorized Person

                                       18
<PAGE>

IN WITNESS WHEREOF, the parties have executed this Agreement as of the date
first written above.

LEHMAN BROTHERS INC.

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

BANK OF AMERICA BRIDGE LLC

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

BANK OF AMERICA SECURITIES LLC

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

CREDIT SUISSE FIRST BOSTON CORPORATION

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

CREDIT SUISSE FIRST BOSTON, CAYMAN ISLANDS
BRANCH

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

                                        LEHMAN COMMERCIAL PAPER INC.,
                                          as Administrative Agent

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

                                       19<PAGE>

                          SUPPLEMENTAL INDENTURE TO BE
                             DELIVERED BY GUARANTORS

     SUPPLEMENTAL INDENTURE (this "Supplemental Indenture"), dated as of
November 9, 2001, among Coleman Research Corporation, a Florida corporation, EER
Systems, Inc., a Virginia corporation, Electrodynamics, Inc., an Arizona
corporation, Henschel Inc., a Delaware corporation, Hygienetics Environmental
Services, Inc., a Delaware corporation, Interstate Electronics Corporation, a
California corporation, KDI Precision Products, Inc., a Delaware corporation,
L-3 Communications Corporation, a Delaware corporation, L-3 Communications Aydin
Corporation, a Delaware corporation, L-3 Communications DBS Microwave, Inc., a
California corporation, L-3 Communications ESSCO, Inc., a Delaware corporation,
L-3 Communications ILEX Systems, Inc., a Delaware corporation, L-3
Communications SPD Technologies, Inc., a Delaware corporation, L-3
Communications Storm Control Systems, Inc., a California corporation, Microdyne
Corporation, a Maryland corporation, MPRI, Inc., a Delaware corporation, Pac Ord
Inc., a Delaware corporation, Power Paragon, Inc., a Delaware corporation,
Southern California Microwave, Inc., a California corporation, SPD Electrical
Systems, Inc., a Delaware corporation, SPD Holdings, Inc., a Delaware
corporation and SPD Switchgear Inc., a Delaware corporation, (each, a
"Guarantor," and collectively, the "Guarantors"), each an indirect subsidiary of
L-3 Communications Holdings, Inc. (or its permitted successor), a Delaware
corporation (the "Company"), the Company 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 21, 2000 providing for the
issuance of an aggregate principal amount of up to $300,000,000 of 5 1/4%
Convertible Senior Subordinated Notes due 2009 (the "Notes");

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

     WHEREAS, pursuant to Section 14.7 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
Guarantors and the Trustee mutually covenant and agree for the equal and ratable
benefit of the Holders of the Notes as follows:

<PAGE>
                                       2

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

     2. AGREEMENT TO GUARANTEE. Each Guarantor hereby agrees as follows:

     (a)  Each Guarantor, jointly and severally with all other current and
          future guarantors of the Notes (collectively, the "Guaranteeing
          Subsidiaries" and each, a "Guaranteeing Subsidiary"), 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 amounts, 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
               Liquidated Damages, 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 Guarantee would
          constitute or result in a violation of any applicable fraudulent
          conveyance or similar law of any relevant jurisdiction, the liability
          of each Guarantor under this Supplemental Indenture and its Guarantee
          shall be reduced to the maximum amount permissible under such
          fraudulent conveyance or similar law.

     3. EXECUTION AND DELIVERY OF GUARANTEES.

     (a)  To evidence its Guarantee set forth in this Supplemental Indenture,
          each Guarantor hereby agrees that a notation of such Guarantee, the
          form of which is included in the Form of Security attached as Exhibit
          A to the Indenture, shall be endorsed by an officer of such Guarantor
          on each Note authenticated and delivered by the Trustee after the date
          hereof.

     (b)  Notwithstanding the foregoing, each Guarantor hereby agrees that its
          Guarantee set forth herein shall remain in full force and effect
          notwithstanding any failure to endorse on each Note a notation of such
          Guarantee.
<PAGE>
                                       3

     (c)  If an Officer whose signature is on this Supplemental Indenture or on
          the Guarantee no longer holds that office at the time the Trustee
          authenticates the Note on which a Guarantee is endorsed, the 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
          Guarantee set forth in this Supplemental Indenture on behalf of each
          Guarantor.

     (e)  Each Guarantor 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 by any Holder of the
          Notes with respect to any provisions of the Notes or the Indenture,
          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 Guarantor 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 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 Guarantor, or any Custodian, Trustee,
          liquidator or other similar official acting in relation to either the
          Company or such Guarantor, any amount paid by either to the Trustee or
          such Holder, the Guarantee made pursuant to this Supplemental
          Indenture, to the extent theretofore discharged, shall be reinstated
          in full force and effect.

     (h)  Each Guarantor 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 Guarantor further agrees that, as between such Guarantor,
          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 4 of the Indenture for the
               purposes of the Guarantee made pursuant to this Supplemental
               Indenture, notwithstanding any stay, injunction or other
               prohibition preventing such acceleration in respect of the
               obligations guaranteed hereby;
<PAGE>
                                       4

          (ii) in the event of any declaration of acceleration of such
               obligations as provided in Article 4 of the Indenture, such
               obligations (whether or not due and payable) shall forthwith
               become due and payable by such Guarantor for the purpose of the
               Guarantee made pursuant to this Supplemental Indenture; and

         (iii) each Guarantor shall have the right to seek contribution from
               any other non-paying Guarantor so long as the exercise of such
               right does not impair the rights of the Holders or the Trustee
               under the Guarantee made pursuant to this Supplemental Indenture.

     4. GUARANTORS MAY CONSOLIDATE, ETC. ON CERTAIN TERMS.

     (a)  Except as set forth in Articles 6 and 9 of the Indenture, nothing
          contained in the Indenture, this Supplemental Indenture or in the
          Notes shall prevent (a) any consolidation or merger of any Guarantor
          with or into the Company or any other Guaranteeing Subsidiary, (b) any
          transfer, sale or conveyance of the property of any Guarantor as an
          entirety or substantially as an entirety, to the Company or any other
          Guaranteeing Subsidiary or (c) any merger of a Guarantor with or into
          an Affiliate of that Guarantor in another State of the United States
          so long as the amount of Indebtedness of the Company and the domestic
          non-Guarantor subsidiaries is not increased thereby.

     (b)  Except as set forth in Article 9 of the Indenture, nothing contained
          in the Indenture, this Supplemental Indenture or in the Notes shall
          prevent any consolidation or merger of any Guarantor with or into a
          corporation or corporations other than the Company or any other
          Guaranteeing Subsidiary (in each case, whether or not affiliated with
          the Guarantor), or successive consolidations or mergers in which a
          Guarantor or its successor or successors shall be a party or parties,
          or shall prevent any sale or conveyance of the property of any
          Guarantor as an entirety or substantially as an entirety, to a
          corporation other than the Company or any other Guaranteeing
          Subsidiary (in each case, whether or not affiliated with the
          Guarantor) authorized to acquire and operate the same; provided,
          however, that each Guarantor hereby covenants and agrees that (i)
          subject to the Indenture, upon any such consolidation, merger, sale or
          conveyance, the due and punctual performance and observance of all of
          the covenants and conditions of the Indenture and this Supplemental
          Indenture to be performed by such Guarantor, shall be expressly
          assumed (in the event that such Guarantor is not the surviving
          corporation in the merger), by supplemental indenture satisfactory in
          form to the Trustee, executed and delivered to the Trustee, by the
          corporation formed by such consolidation, or into which such Guarantor
          shall have been merged, or by the corporation which shall have
          acquired such property, (ii) immediately after giving effect to such
          consolidation, merger, sale or conveyance no Default or Event of
          Default exists, and (iii) such transaction will only be

<PAGE>
                                       5

          permitted under the Indenture and this Supplemental Indenture if it
          would be permitted under the terms of all of the indentures governing
          the Outstanding Senior Subordinated Notes as the same are in effect on
          the date hereof (whether or not those indentures are subsequently
          amended, waived, modified or terminated or expire and whether or not
          any of these notes continue to be outstanding).

     (c)  In case of any such consolidation, merger, sale or conveyance and upon
          the assumption by the successor corporation, by supplemental
          indenture, executed and delivered to the Trustee and satisfactory in
          form to the Trustee, of the Guarantee made pursuant to this
          Supplemental Indenture and the due and punctual performance of all of
          the covenants and conditions of the Indenture and this Supplemental
          Indenture to be performed by each Guarantor, such successor
          corporation shall succeed to and be substituted for such Guarantor
          with the same effect as if it had been named herein as one of the
          Guarantors. Such successor corporation thereupon may cause to be
          signed any or all of the Guarantees to be endorsed upon the Notes
          issuable under the Indenture which theretofore shall not have been
          signed by the Company and delivered to the Trustee. All the Guarantees
          so issued shall in all respects have the same legal rank and benefit
          under the Indenture and this Supplemental Indenture as the Guarantees
          theretofore and thereafter issued in accordance with the terms of the
          Indenture and this Supplemental Indenture as though all of such
          Guarantees had been issued at the date of the execution hereof.

     5. RELEASES.

     (a)  Concurrently with any sale of assets (including, if applicable, all of
          the Capital Stock of a Guarantor), all Liens, if any, in favor of the
          Trustee in the assets sold thereby shall be released. If the assets
          sold in such sale or other disposition include all or substantially
          all of the assets of a Guarantor or all of the Capital Stock of a
          Guarantor, then the Guarantor (in the event of a sale or other
          disposition of all of the Capital Stock of such Guarantor) or the
          Person acquiring the property (in the event of a sale or other
          disposition of all or substantially all of the assets of such
          Guarantor) shall be released from and relieved of its obligations
          under this Supplemental Indenture and its Guarantee made pursuant
          hereto. Upon delivery by the Company to the Trustee of an Officers"
          Certificate to the effect that such sale or other disposition was made
          by the Company or the Guarantor, as the case may be, in accordance
          with the provisions of the Indenture and this Supplemental Indenture,
          the Trustee shall execute any documents reasonably required in order
          to evidence the release of the Guarantor from its obligations under
          this Supplemental Indenture and its Guarantee made pursuant hereto. If
          the Guarantor is not released from its obligations under its
          Guarantee, it shall remain liable for the full amount of principal of
          and interest on the Notes and for the other obligations of such
          Guarantor under the Indenture as provided in this Supplemental
          Indenture.
<PAGE>
                                       6

     (b)  Upon the designation of a Guarantor as an Excluded Subsidiary in
          accordance with the terms of the Indenture and the indentures
          governing the Outstanding Senior Subordinated Notes as the same are in
          effect on the date hereof (whether or not those indentures are
          subsequently amended, waived, modified or terminated or expire and
          whether or not any of those notes continue to be outstanding), such
          Guarantor shall be released and relieved of its obligations under the
          Indenture and this Supplemental Indenture. Upon delivery by the
          Company to the Trustee of an Officers" Certificate and an Opinion of
          Counsel to the effect that such designation of such Guarantor as an
          Excluded Subsidiary was made by the Company in accordance with the
          provisions of the Indenture and the indentures governing the
          Outstanding Senior Subordinated Notes as the same are in effect on the
          date hereof (whether or not those indentures are subsequently amended,
          waived, modified, terminated or expired and whether or not any of
          those notes continue to be outstanding), the Trustee shall execute any
          documents reasonably required in order to evidence the release of such
          Guarantor from its obligations under its Guarantee. Any Guarantor not
          released from its obligations under its Guarantee shall remain liable
          for the full amount of principal of and interest on the Notes and for
          the other obligations of any Guarantor under the Indenture as provided
          herein.

     6. NO RECOURSE AGAINST OTHERS. No past, present or future director,
officer, employee, incorporator, stockholder or agent of any Guarantor, as such,
shall have any liability for any obligations of the Company or any Guarantor
under the Notes, any Guarantees, the Indenture or this Supplemental Indenture or
for any claim based on, in respect of, or by reason of, such obligations or
their creation. Each Holder of the Notes by accepting a Note waives and releases
all such liability. The waiver and release are part of the consideration for
issuance of the Notes. Such waiver may not be effective to waive liabilities
under the federal securities laws and it is the view of the Commission that such
a waiver is against public policy.

     7. SUBORDINATION OF GUARANTEES; ANTI-LAYERING. No Guarantor shall incur,
create, issue, assume, guarantee or otherwise become liable for any Indebtedness
that is subordinate or junior in right of payment to any Senior Debt of a
Guarantor and senior in any respect in right of payment to any of the
Guarantees. Notwithstanding the foregoing sentence, the Guarantee of each
Guarantor shall be subordinated to the prior payment in full of all Senior Debt
of that Guarantor, which shall include all guarantees of Senior Debt.

     8. THIS SUPPLEMENTAL INDENTURE SHALL BE GOVERNED BY, AND CONSTRUED IN
ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK.

     9. COUNTERPARTS. The parties may sign any number of copies of this
Supplemental Indenture. Each signed copy shall be an original, but all of them
together represent the same agreement.

     10. EFFECT OF HEADINGS. The Section headings herein are for convenience
only and shall not affect the construction hereof.
<PAGE>
                                       7

     11. THE TRUSTEE. The Trustee shall not be responsible in any manner
whatsoever for or in respect of the validity or sufficiency of this Supplemental
Indenture or for or in respect of the recitals contained herein, all of which
recitals are made solely by the Guarantors and the Company.

<PAGE>
                                       8

     IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture to be duly executed and attested, all as of the date first above
written.

Dated: November 9, 2001

                                 L-3 COMMUNICATIONS HOLDINGS, INC.

                                 By: ______________________________________
                                     Name:
                                     Title:

                                 COLEMAN RESEARCH CORPORATION
                                 EER SYSTEMS, INC.
                                 ELECTRODYNAMICS, INC.
                                 HENSCHEL INC.
                                 HYGIENETICS ENVIRONMENTAL SERVICES,
                                         INC.
                                 INTERSTATE ELECTRONICS CORPORATION
                                 KDI PRECISION PRODUCTS, INC.
                                 L-3 COMMUNICATIONS CORPORATION
                                 L-3 COMMUNICATIONS AYDIN
                                        CORPORATION
                                 L-3 COMMUNICATIONS DBS MICROWAVE,
                                        INC.
                                 L-3 COMMUNICATIONS ESSCO, INC.
                                 L-3 COMMUNICATIONS ILEX SYSTEMS, INC.
                                 L-3 COMMUNICATIONS SPD
                                        TECHNOLOGIES, INC.
                                 L-3 COMMUNICATIONS STORM CONTROL
                                        SYSTEMS, INC.
                                 MICRODYNE CORPORATION
                                 MPRI, INC.
                                 PAC ORD INC.
                                 POWER PARAGON, INC.
                                 SOUTHERN CALIFORNIA MICROWAVE, INC.
                                 SPD ELECTRICAL SYSTEMS, INC.
                                 SPD HOLDINGS, INC.
                                 SPD SWITCHGEAR INC.
                                        As Guaranteeing Subsidiaries

                                 By: ______________________________________
                                     Name:
                                     Title:

<PAGE>
                                       9

Dated:  November 9, 2001          THE BANK OF NEW YORK
                                  as Trustee

                                  By: ______________________________________
                                      Name:
                                      Title:

<PAGE>

                      NOTATION ON SENIOR SUBORDINATED NOTE
                             RELATING TO GUARANTEE

     Pursuant to the Supplemental Indenture (the "Supplemental Indenture") dated
as of November 9, 2001 among L-3 Communications Holdings, Inc., a Delaware
corporation, Coleman Research Corporation, a Florida corporation, EER Systems,
Inc., a Virginia corporation, Electrodynamics, Inc., an Arizona corporation,
Henschel Inc., a Delaware corporation, Hygienetics Environmental Services, Inc.,
a Delaware corporation, Interstate Electronics Corporation, a California
corporation, KDI Precision Products, Inc., a Delaware corporation, L-3
Communications Corporation, a Delaware corporation, L-3 Communications Aydin
Corporation, a Delaware corporation, L-3 Communications DBS Microwave, Inc., a
California corporation, L-3 Communications ESSCO, Inc., a Delaware corporation,
L-3 Communications ILEX Systems, Inc., a Delaware corporation, L-3
Communications SPD Technologies, Inc., a Delaware corporation, L-3
Communications Storm Control Systems, Inc., a California corporation, Microdyne
Corporation, a Maryland corporation, MPRI, Inc., a Delaware corporation, Pac Ord
Inc., a Delaware corporation, Power Paragon, Inc., a Delaware corporation,
Southern California Microwave, Inc., a California corporation, SPD Electrical
Systems, Inc., a Delaware corporation, SPD Holdings, Inc., a Delaware
corporation and SPD Switchgear Inc., a Delaware corporation, and The Bank of New
York, each Guarantor (i) has jointly and severally unconditionally guaranteed
(a) the due and punctual payment of the principal of, and premium, interest and
Liquidated Damages on the Notes, whether at maturity or an interest payment
date, by acceleration, call for redemption or otherwise, (b) the due and
punctual payment of interest on the overdue principal and premium of, and
interest and Liquidated Damages on the Notes, and (c) in case of any extension
of time of payment or renewal of any Notes or any of such other obligations, 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
and (ii) has agreed to pay any and all costs and expenses (including reasonable
attorneys" fees) incurred by the Trustee or any Holder in enforcing any rights
under this Guarantee.

     Notwithstanding the foregoing, in the event that the Guarantee of any
Guarantor would constitute or result in a violation of any applicable fraudulent
conveyance or similar law of any relevant jurisdiction, the liability of such
Guarantor under its Guarantee shall be reduced to the maximum amount permissible
under such fraudulent conveyance or similar law.

     No past, present or future director, officer, employee, agent,
incorporator, stockholder or agent of any Guarantor, as such, shall have any
liability for any obligations of the Company or any Guarantor under the Notes,
any Guarantee, the Indenture, any supplemental indenture delivered pursuant to
the Indenture by such Guarantor or any Guarantees, or for any claim based on, in
respect of or by reason of such obligations or their creation. Each Holder by
accepting a Note waives and releases all such liability.

     This Guarantee shall be binding upon each Guarantor and its successors and
assigns and shall inure to the benefit of the successors and assigns of the
Trustee and the Holders and, in the event of any transfer or assignment of
rights by any Holder or the Trustee, the rights and privileges herein conferred
upon that party shall automatically extend to and be vested in such transferee
or assignee, all subject to the terms and conditions hereof.
<PAGE>

     This Guarantee shall not be valid or obligatory for any purpose until the
certificate of authentication on the Note upon which this Guarantee is noted
have been executed by the Trustee under the Indenture by the manual signature of
one of its authorized officers. Capitalized terms used herein have the meaning
assigned to them in the Indenture.

<PAGE>

                                    COLEMAN RESEARCH CORPORATION
                                    EER SYSTEMS, INC.
                                    ELECTRODYNAMICS, INC.
                                    HENSCHEL INC.
                                    HYGIENETICS ENVIRONMENTAL SERVICES,
                                           INC.
                                    INTERSTATE ELECTRONICS CORPORATION
                                    KDI PRECISION PRODUCTS, INC.
                                    L-3 COMMUNICATIONS AYDIN
                                           CORPORATION
                                    L-3 COMMUNICATIONS DBS MICROWAVE,
                                           INC.
                                    L-3 COMMUNICATIONS ESSCO, INC.
                                    L-3 COMMUNICATIONS ILEX SYSTEMS, INC.
                                    L-3 COMMUNICATIONS SPD
                                           TECHNOLOGIES, INC.
                                    L-3 COMMUNICATIONS STORM CONTROL
                                           SYSTEMS, INC.
                                    MICRODYNE CORPORATION
                                    MPRI, INC.
                                    PAC ORD INC.
                                    POWER PARAGON, INC.
                                    SOUTHERN CALIFORNIA MICROWAVE, INC.
                                    SPD ELECTRICAL SYSTEMS, INC.
                                    SPD HOLDINGS, INC.
                                    SPD SWITCHGEAR INC.
                                             As Guaranteeing Subsidiaries

                                    By: ______________________________________
                                           Name:
                                           Title:

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