TEKTON 3-PC. IMPACT REDUCER SET features: Drop-Forged, Heat Treated Steel, Oil-Quenched, Black-Oxide Finish for Durability, Spring-Loaded Ball Bearings Hold Sockets Securely, Hole on Reducers for Locking onto Drive Tang, Specially Designed for Use with Air Tools, 1-pc. 3/8"(F) x 1/4"(M), 1-pc. 1/2"(F) x 3/8"(M), 1-pc. 3/4"(F) x 1/2"(M).