Features: inner square with external hexagon drive in accordance with DIN 3126 / ISO 1173 shape - C 6.35For manual actuation and electric screwdrivers, ideal for screws in craft and industrial reinforced design, nickel-plated, special tool steel, technical data: square drive: 1/4 inch, diameter: 12 mm, shape: knurled, weight: 20 g, total length: 37.0 mm, material: fine chrome vanadium steel, high gloss finish included.