Built for maximum durability and long life with impact drivers. Adapts standard 1/4″ square drive chucks to 1/4″ hex drive chuck that are compatible with impact drilling accessories. Patented jaw design is compatible with all 1/4″ hex shank accessories including insert bits. Large chuck withstands higher torque demands of impact drivers. Black oxide finish resists corrosion and increases life of bit. Square drive 14 to 1/4.