These Armstrong 9" Wiretwister, Automatic, Diagonal Nose, Right Hand Twist have induction hardened cutting edges especially designed for cutting stainless steel safety wire, diamond serrations on the jaws that hold wire securely and resist nicking, an automatic spring return, and a diagonal nose that allows access in tight work areas. Wire twister pliers and safety wire are used for safety-wiring fasteners in aviation and other applications such as engines, gearboxes or any assembly where vibration may cause fasteners to back out.