TEKTON 4957 Impact Adapter and Reducer Set features: Drop Forged, Heat Treated Chrome Vanadium Steel, Oil-Quenched, Black-Oxide Finished for Durability, Hole on Reducers for Locking onto Drive Tang, Specially Designed for Use with Air Tools, Spring-Loaded Ball Bearings Hold Sockets Securely, 2-pc. Impact Reducer: 1/2"(F) x 3/8"(M), 3/8"(F) x 1/4"(M), 2-pc. Impact Adapter: 3/8"(F) x 1/2"(M), 1/4"(F) x 3/8"(M)