Bit holder 5/16", 1/2" type no. 543

Socket, hexagon 5/16" inside hexagon, DIN 3126/ISO 1173 D 8. Internal hex drive with a collar-thrust spring (registered design). Bits are easy to insert, lock securely in position and can be removed just as easily; even hex bits with a wide groove (Type E, DIN 3126/ISO 1173).