The requirement is for NSN 7R-6635-015840561-SX, TDP VER 004, quantity 6 EA, with delivery FOB origin. The item is flight critical and/or lacks adequate technical data for full and open competition, so Government source approval is required prior to award and only previously approved sources have been solicited. Non-approved sources must submit the information required by the applicable NAVSUP WSS Source Approval Information Brochure with their proposal; offers lacking the required data or prior submission documentation will not be considered. Standardized documents are available through DODSSP/ASSIST, with DODSSP document services located in Philadelphia, PA. Award requires the offeror, product/service, or manufacturer to meet qualification requirements at time of award under FAR clause 52.209-1, and FAR Part 12 commercial-item policies are not being used, though interested parties may identify commercial-item interest and capability to the contracting officer.