Sturdy shape especially for use with electric or compressed air impact wrenches. With cross hole and snap ring groove for securing sockets. Internal square to DIN 3121.
For safety reasons must always be secured using a suitable locking pin and O-ring.
The surface drive profile grips the bolt on the faces and protects the weaker corners. This reliably prevents the socket jamming or damaging the bolt heads.
Chrome molybdenum steel, surface burnished.