Back Home / Tools and Equipment / Hand Tools / CHUCK KEY – LARGE MASTER, 3/8″- 3/4″ CHUCK KEY – LARGE MASTER, 3/8″- 3/4″ SKU: MCKL Categories: Hand Tools, Tools and Equipment Carbon steel master chuck key. Opens heavy duty chucks 3/8″ to 3/4″. The squared center of the key opens acetylene tanks. Made from carbon steel. Carbon steel master chuck key. Opens heavy duty chucks 3/8″ to 3/4″. The squared center of the key opens acetylene tanks. Made from carbon steel. Case Quantity: 1 Log In For Pricing