Irwin Professional Speed Clamp has an I-Beam / Ribbed Design which provides higher mechanical strength. Less failure than other speed clamps. Removable Pads snap fit to prevent loss and provide excellent grip to the work surface, whilst reducing marking of the workpiece. The 3 Component Handle (small and medium ranges) has a soft grip for added comfort. Provides better grip than wood, enabling user to increase twist and obtain higher clamping force. The investment casting is stronger than sand casting. Whilst the patented floating lock gives increased safety and eliminates slippage. The flat feet design is easier-to-use and enables free standing of the clamp both horizontally and vertically. It is zinc plated to prevent rust and increase lifespan. Throat: 120mm (5in).Irwin Professional Speed Clamp Medium. Capacity: 300mm (12 in).