Ductile Iron C Clamps-light duty for woodwork and high-performance clamping Ductile Iron C Clamps-light duty:frame made from ductile iron castings with high strength,Sliding pin handle, single acme thread rolled spindle with good performance.All sizes are with good finish by powder coating, the screws can be treated bychome-plated, zinc-plated, copper-plated or black-oxidized.