3-Step RTA Furniture Drill/Countersink Assemblywith HSS Slow Spiral Drill Commonly used for RTA (ready-to-assemble) furniture fittings. Specially-treated high-speed steel countersink with polished slow-spiral drill bit. Will perform 3 tasks in one: pilot hole, clearance hole and countersink. For connecting screws (Confirmat, Directa, etc.). The shank-less countersink is heat treated. *B can be adjusted up to 30mm.