Rugged & Reliable: Heavy duty chrome plated carbon steel and aluminum alloy construction allow for years of usage with no rust or wear. Hardened sharp steel teeth will not get dull or broken after repeated usage Create Precise Miter Joint: Turn the lever with ergonomic large knob to make inside cam rotate. The rotating cam pushes the bar out, through which four sharp teeth are evenly threaded. The four hardened teeth easily penetrate the wood for firm grip and bars put very high pressure all across the miter joint for a precise glue joint .