The government seeks a Firm Fixed Price, Indefinite Delivery Indefinite Quantity contract for an Insulation, Thermal spare part, with an estimated quantity ranging from 177 each minimum to 1,415 each maximum. Delivery is expected 30 days from award, with shipments to addresses within the continental United States and a 60-month period of performance. Acquisition will be restricted to two approved sources: The Boeing Company and Thermal Structures, Inc., as the government does not own the technical data package and reverse engineering is not feasible. The award will be made via sealed bidding without discussions, so initial bids must be most favorable. This is a presolicitation notice only; the solicitation will be posted electronically on SAM.gov.