for bit screwdriver inserts with external hexagon 1/4" DIN 3126/ISO 1173 form C 6.31/4" sockets can be used with connector No. 3115/1 (external hexagon and external square 1/4")switching ring for easy change of direction (left, right and fixed)ergonomically designed, slip-resistant 2-component handle for optimum force transfereasy bit changing with the magnetic inner hexagonhigh load mechanism with 48 teeth (7.5° working angle)