W.L. Fuller Countersinks are designed for clean cutting and are hardened for long wear, They can be mounted on Taper point drills or straight twist drills. The countersink is held in place with two hex-socket screws and is easily adjustable up and down the drill so that only one countersink and one length of drill is required for any length of wood screw. Set includes Countersink, Stop Collar, Tapered Drill Bit and Allen Wrench.