I have a USGI M16 bolt carrier that I purchased NIW in the mid-80’s. I removed it from the wrapper so it is old but like new and has never been in an upper receiver. The key came installed but unstaked. It is marked [SE] (Smith Enterprises). It was torqued and properly staked using a MOACK during Dean Caputo’s Boone County Class. Price is $106, delivered with Delivery Confirmation (please add $4.00 for paypal).