This adapter was specific for the 5 series L-J's. This part is designed to be used with the Mercury Redstone capsule re-released by Estes in the Mercury Redstone kit, and the Little Joe fin Unit
, that I have designed for the booster. It should altogether make for an easy and fun Little Joe LJ-5,5A,5B. The adapter is meant to be a direct shoulder bearing for the nose cone. It is sized for a BT-70 airframe to match with my Little Joe fin unit.