The open end anti-slip helps prevent the open end of the wrench from slipping off the bolt. The corner of the bolt is locked in the head of the groove. As soon as torque is applied to the closure, the head of the locks on making it virtually impossible for the head to slip. Inner arc profile creates large contact areas help extend the life of fasteners. Helps increase productivity and efficiency. Less risk of injury to phalanx from hitting the binding. Less damage and rounding to bindings. Spring Box end prevents passing through or slipping off the bolt, however the innovative design allows passing through the nut to have access to a second nut if necessary. 15 degree offset angle gives ultimate access to raised, recessed or closely spaced fasteners. Better comfort with less stress to the hand. Higher strength for increased safety. Allows the user to apply more torque. Same pattern as the Facom 440 range. Easy to clean. Prevents corrosion. Lifetime guarantee. Sizes: 8, 10, 11, 12, 13, 14, 17 and 19 mm, supplied in Facom storage clip.