Not only the opening (hexagonal) in contact with the bolt/nut, but also the square drive on the insertion side has a flat drive with a surface contact that reliably conveys high torque without damaging corners.
Specifications
Insertion angle (mm): 12.7
Opposite size (mm): 36
Total length (mm): 46
Applicable C Ring: PK 1401 C (opposite side 10, to 14, mm), PK 1402 C (opposite side 17, to 36, mm)