The router bits in this money-saving set features K10 and K20 grade carbide for clean cutting action and final sharpened with 400 grit diamond wheels for longer cutting life. All with 1/4″ shanks.Biscuit Cutter Set includes cutter and all three bearings to cut biscuit slots for 0, 10 and 20 size biscuits. All have baked-on Teflon coating to reduce pitch and resin buildup.Rockler router bits are unconditionally guaranteed – if you are not 100 percent satisfied with these bits, send them back for a full refund.