This is a sole-source procurement for five units of an NSN part that requires engineering source approval due to flight-criticality and limited data rights. Only previously approved sources are solicited; alternate sources must qualify through government-approved procedures, but award cannot be delayed for new approvals. Unapproved offerors must submit detailed source approval information with their proposal, or they will not be considered. The government will review capability statements to decide whether competition is possible, but this notice is not a request for competitive proposals. Delivery terms are FOB origin, and no budget amount or performance location is specified.