The Cam Clamps for T-Tracks (D3347) have been used on CNC machines as work holding fixtures for decades. The clamp acts on an eccentric cam, which tightens the jaw as the handle is moved. The jaw is set on an angle and provides inward/downward pressure to apply the “grip of death” on your project. Easy to set up, slides along on tracks and leaves the top of your project unobstructed. Made of hardened steel.