The CRL Fletcher® Thick Glass Breaker Tool portable breaking tool "runs" your score line with precise control. After scoring the glass, mount the breaker on the glass with the screw knob facing down. Spread the two silver round anvils as far apart as possible, locating the pointed silver fulcrum directly under the score line. Turn the black knob so that the fulcrum presses upward on the glass from below. The BR1 is guaranteed to produce a clean edge every time. There is no crushing of the glass edge or breaking of your glass sheet. It comes complete with a carbide glass cutter with a 148 degree angle wheel for cutting glass up to 1" (25.4 mm) thick.