The CRL TOYO Tap Wheel™ Thick Glass Supercutter Cutter is an automatic oil-feed Glass Cutter designed for 1/2" to 3/4" (12 to 19 mm) thick glass. The Tap Wheel™ Technology employs eight cams inside the axle bore of a 153 degree cutting wheel. These cams produce a slight vibration or "tap" during the score. The result is longer wheel life, deeper, cleaner, more consistent scoring, improved breakout and edge quality. While scoring, the reservoir oil-fill cap should be opened a 1/2" turn to improve oil flow. As with all self-oiling cutters, the first use requires priming the oil system by depressing the cutting head several times until oil reaches the wheel.