With square drive according to DIN 3120 - C 12.5, ISO 1174, GEDORE vanadium steel 31CrV3, VDE insulation up to 1000 V, acc. to EN 60900/IEC 60900, two-ply Check-Tool insulation, 16 - 18 mm insulation overhang, Sizes 27, 30 and 32: diameter d1 is not standardised, The diameter d1 for the dimensions 27, 30 and 32 is not standardized