Filed Pursuant to Rule 424(b)(2) Registration File No.: 333-58328 PROSPECTUS SUPPLEMENT (TO PROSPECTUS DATED APRIL 12, 2001) Dated December 12, 2001 $300,000,000 [L-3 COMMUNICATIONS HOLDINGS, INC. LOGO] L-3 COMMUNICATIONS HOLDINGS, INC. 5.25% CONVERTIBLE SENIOR SUBORDINATED NOTES DUE 2009 AND 3,680,982 SHARES OF COMMON STOCK ISSUABLE UPON CONVERSION OF THE NOTES Guaranteed by L-3 Communications Corporation L-3 Communications Storm Control Systems, Inc. Electrodynamics, Inc. Microdyne Corporation Henschel, Inc. MPRI, Inc. Hygienetics Environmental Services, Inc. Pac Ord, Inc. Interstate Electronics Corporation Power Paragon, Inc. L-3 Communications DBS Microwave, Inc. Southern California Microwave, Inc. L-3 Communications ESSCO, Inc. SPD Holdings, Inc. L-3 Communications ILEX Systems, Inc. SPD Electrical Systems, Inc. L-3 Communications Aydin Corporation SPD Switchgear, Inc. L-3 Communications SPD Technologies, Inc. -------------------------------------------------------------------------------- This prospectus supplement relates to: -- $300,000,000 principal amount of 5.25% convertible senior subordinated notes due 2009; -- The shares of our common stock issuable upon conversion of the notes; and -- The subsidiary guarantees of the notes on behalf of each of our subsidiary guarantors. This prospectus supplement, which supplements our prospectus dated April 12, 2001, contains information about the selling security holders. NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES COMMISSION HAS APPROVED OR DISAPPROVED OF THESE SECURITIES OR DETERMINED IF THIS PROSPECTUS SUPPLEMENT IS TRUTHFUL OR COMPLETE. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE. -------------------------------------------------------------------------------- December 12, 2001 TABLE OF CONTENTS PAGE ---- Selling Security Holders ................................................ S-3 --------------------- You should rely only on the information contained in this prospectus supplement and the prospectus to which it refers. We have not authorized any other person to provide you with different information. If anyone provides you with different or inconsistent information, you should not rely on it. We are not making an offer to sell these securities in any jurisdiction where the offer or sale is not permitted. You should assume that the information appearing in this prospectus supplement and the prospectus to which it refers is accurate only as of their respective dates. S-2 SELLING SECURITY HOLDERS The following table sets forth information, as of December 12, 2001, with respect to the selling holders and the principal amounts of notes beneficially owned by each selling holder that may be offered under this prospectus. The information is based on information provided by or on behalf of the selling holders. The selling holders may offer all, some or none of the notes or common stock into which the notes are convertible. Because the selling holders may offer all or some portion of the notes or the common stock, no estimate can be given as to the amount of the notes or the common stock that will be held by the selling holders upon termination of any sales. In addition, the selling holders identified below may have sold, transferred or otherwise disposed of all or a portion of their notes in transactions exempt from the registration requirements of the Securities Act. Selling holders, including their transferees, pledgees or donees or their successors, may from time to time offer and sell pursuant to this prospectus any or all of the notes and common stock into which the notes are convertible. PRINCIPAL AMOUNT OF COMMON NOTES PERCENT OF STOCK ISSUABLE BENEFICIALLY THE NOTES UPON CONVERSION NAME OWNED OWNED OF THE NOTES ---- -------------- ------------ ---------------- 1976 Distribution Trust FBO A. R. Lauder Zinterhofer ................................... $ 8,000 -- 98 1976 Distribution Trust FBO Jane A. Lauder ................... $ 16,000 0.01% 196 2000 Revocable Trust FBO A. R. Lauder Zinterhofer ................................... $ 8,000 -- 98 ABN Amro Securities LLC ...................................... $ 6,000,000 2.00% 73,619 ACM Offshore Fund ............................................ $ 850,000 0.28% 10,429 AIG/National Union Fire Insurance ............................ $ 785,000 0.26% 9,631 Alexandra Global Investment Fund 1 Ltd ....................... $ 6,500,000 2.16% 79,754 Aloha Airlines Non-Pilots Pension Trust ...................... $ 175,000 0.06% 2,147 Aloha Pilots Retirement Trust ................................ $ 100,000 0.03% 1,226 Alpha U.S. Sub Fund VIII, LLC ................................ $ 750,000 0.25% 9,202 Alpine Associates ............................................ $ 4,000,000 1.33% 49,079 Alpine Partners, L.P. ........................................ $ 650,000 0.22% 7,975 Allstate Insurance Company ................................... $ 1,000,000 0.33% 12,269 Allstate Life Insurance Company .............................. $ 400,000 0.13% 4,907 Amaranth Securities L.L.C. ................................... $ 5,000,000 1.67% 61,349 American Motorist Insurance Corporation ...................... $ 585,000 0.20% 7,177 Arapahoe County, Colorado .................................... $ 57,000 0.02% 699 Arbitex Master Fund, L.P. .................................... $ 6,400,000 2.13% 78,527 Arkansas PERS ................................................ $ 950,000 0.32% 11,656 Arkansas Teachers Retirement ................................. $ 3,885,000 1.30% 47,668 Associated Electric & Gas Insurance Services Limited ......... $ 500,000 0.17% 6,134 BP Amoco Corporation Master Trust for Employee Pension Plans ................................................ $ 7,700,000 2.56% 94,478 BP Amoco PLC, Master Trust ................................... $ 410,000 0.14% 5,030 BT Equity Opportunities ...................................... $ 2,000,000 0.67% 24,539 BT Strategy .................................................. $ 1,000,000 0.33% 12,269 Bancroft Convertible Fund, Inc. .............................. $ 1,000,000 0.33% 12,269 Bank Austria Cayman Islands* ................................. $ 4,500,000 1.50% 55,214 S-3 PRINCIPAL AMOUNT OF COMMON NOTES PERCENT OF STOCK ISSUABLE BENEFICIALLY THE NOTES UPON CONVERSION NAME OWNED OWNED OF THE NOTES ---- -------------------------- ---------------- Baptist Health of South Florida .................................................. $ 386,000 0.13% 4,736 Black Diamond Offshore, Ltd. ..................................................... $ 753,000 0.25% 9,239 Boilermakers Blacksmith Pension Trust ............................................ $ 1,300,000 0.43% 15,950 Boston Museum of Fine Art ........................................................ $ 115,000 0.04% 1,411 Brazos Small Cap Portfolio ....................................................... $12,700,000 4.23% 155,828 British Virgin Islands Social Security Board ..................................... $ 42,000 0.01% 515 C&H Sugar Company Inc. ........................................................... $ 265,000 0.09% 3,251 CALAMOS (Registered Trademark) Convertible Fund -- CALAMOS (Registered Trademark) Investment Trust ........................................ $ 2,920,000 0.97% 35,828 CALAMOS (Registered Trademark) Convertible Growth and Income Fund -- CALAMOS (Registered Trademark) Investment Trust ....................... $ 1,500,000 0.50% 18,404 CALAMOS (Registered Trademark) Convertible Portfolio -- CALAMOS (Registered Trademark) Advisors Trust .......................................... $ 200,000 0.06% 2,453 CALAMOS (Registered Trademark) Convertible Technology Fund -- CALAMOS (Registered Trademark) Investment Trust ................................. $ 60,000 0.02% 736 CALAMOS (Registered Trademark) Global Convertible Fund -- CALAMOS (Registered Trademark) Investment Trust ........................................ $ 320,000 0.11% 3,296 Chrysler Corporation Master Retirement Trust ..................................... $ 4,960,000 1.65% 60,858 City of New Orleans .............................................................. $ 239,000 0.08% 2,932 City University of New York ...................................................... $ 142,000 0.05% 1,742 The Class IC Company Ltd. ........................................................ $ 2,750,000 0.92% 33,742 Continental Assurance Company .................................................... $ 2,400,000 0.80% 29,447 Credit Lyonnais Securities (USA) Inc. ............................................ $ 2,000,000 0.67% 24,539 Deephaven Domestic Convertible Trading Ltd. ...................................... $ 8,100,000 2.70% 99,386 Deeprock & Co. ................................................................... $ 1,000,000 0.33% 12,269 Delaware PERS .................................................................... $ 1,400,000 0.47% 17,177 Delta Air Lines Master Trust (c/o Oaktree Capital Management LLC) .................................................................. $ 1,705,000 0.57% 20,920 Delta Pilots D&S Trust ........................................................... $ 605,000 0.20% 7,423 Deutsche Banc Alex Brown Inc. .................................................... $ 9,536,000 2.72% 117,006 Double Black Diamond Offshore, LDC ............................................... $ 3,113,000 1.04% 38,196 Drury University ................................................................. $ 80,000 0.03% 981 Dylan (IMA) Limited .............................................................. $ 2,000,000 0.67% 24,539 Ellsworth Convertible Growth and Income Fund, Inc. ............................... $ 1,000,000 0.33% 12,269 Employee Benefit Convertible Securities Fund ..................................... $ 240,000 0.08% 2,944 Engineers Joint Pension Fund ..................................................... $ 469,000 0.16% 5,754 Enterprise Convertible Securities Fund ........................................... $ 95,000 0.03% 1,165 F. R. Convt. Sec. Fn. ............................................................ $ 95,000 0.03% 1,165 First Union Securities Inc. ...................................................... $ 450,000 0.15% 5,521 Froley Investment Company, Inc. .................................................. $ 235,000 0.08% 2,883 The Grable Foundation ............................................................ $ 111,000 0.04% 1,361 Grady Hospital Foundation ........................................................ $ 122,000 0.04% 1,496 Hawaiian Airlines Employees Pension Plan--IAM .................................... $ 80,000 0.03% 981 Hawaiian Airlines Pension Plan for Salaried Employees ............................ $ 20,000 0.01% 245 Hawaiian Airlines Pilots Retirement Plan ......................................... $ 160,000 0.05% 1,963 HFR Convertible Arbitrage Fund ................................................... $ 200,000 0.07% 2,453 Highbridge International LLC ..................................................... $15,000,000 5.00% 184,049 ICI American Holdings Trust ...................................................... $ 750,000 0.25% 9,202 Independence Blue Cross .......................................................... $ 116,000 0.04% 1,423 S-4