For clean, fast cutting, the bit features four carbide cutters"two main cutters that bore a flat-bottomed hole, and a pair of spur cutters that ensure clean hole edges free of tearout. The bit shank is sized to fit in the drill guide on the concealed hinge jig, and the shank has a shoulder that perfectly positions a stop collar. Additional Features Works with all 35 mm concealed hinges Shank fits perfectly in concealed hinge jig drill guide Shoulder ensures accurate stop-collar positioning (stop collar sold separately with concealed hinge jig) Spurs create clean hole edges without tearout Large carbide cutters bore a flat, smooth hole