Reversible, with inside hexagon 5/16, DIN 3126/ISO 1173 D 8 for Bits Screwdriver sockets 5/16 (30 teeth). Internal hex drive with acollar-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).