Reversible, with inside hexagon,
1/4" or 5/16", DIN 3126/ISO 1173 D 6.3 or D8 for
direct acceptance of bits 1/4" or 5/16"
outside hexagon C 6.3 (size 4: 22 teeth, size 5: 30 teeth).
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).