Heat treated Chrome Molybdenum and Chrome Vanadium steel construction with a nickel-plated smooth satin finish. Deeply serrated and hardened teeth grip the workpiece from any angle. Curved jaw design applies maximum pressure to all four corners of nut or bolt heads making it ideal for high torque applications. Riveted handle construction provides extra rigidity and reduces deformation when grip is under load. Spring loaded locking mechanism prevents nipping fingertips when releasing. Heavily knurled adjustment screw enables extra grip.