The SXT Racing Break In Bit helps to simplify tire break in. This bit locks into your drill and allows you to mount any 12mm hex wheel directly to the drill, so you can sand down your tires with ease. The Break in Bit is just over 4” long so nothing to worry about on clearance. Made from HSS steel with a wide brass hex to keep the wheel stable and locked down with double set screws. The Longest screw is for 1/8 tires, medium screw is for rear 1/10 tires, and the short screw is for front 1/10 tires.