This HD30 Quick Hold Down clamp slides in a 3/4″ wide T-Slot Track and quickly secures with the turn of the hand knob. It provides downward pressure on your workpiece to secure it in place. HD30 has 3 stages of adjustments to meet different thickness workpieces up to 100mm. The clamp foot has rubber pad. The anodized aluminum alloy clamp body is CNC machined, provides wear-resistant, rust-proof and long life.