The Wilton Spark-Duty C-Clamp features spindles and pads that are copper plated to provide resistance to welding splatter and corrosion. The acme rolled spindle threads provide continuous smooth operation and allow faster clamping action with maximum strength. The clamp is ideal for steel fabrication and industrial welders. ADDITIONAL SPECIFICATIONS: Nominal Opening Capacity: 0 - 8-1/4"; Throat Depth: 5"; Clamp Pressure: 6900 lb.; Spindle Size: 3/4"