Shell style 90º countersink produced from the best grade carbon steel designed to leave a clean cut finish by virtue of their multi-tooth deep ground gullets. Not suitable for abrasive materials or metals. This TCT Countersink clamps onto any drill between 3 mm and 7.2 mm in diameter. The drill passes through the body of the countersink and is secured by two hexagon bolts which clamp the countersink onto the drill at the required position. Recommended for wood and man made boards. By reversing the countersink on the drill the UNI / CS can be used as a non-cutting depth stop. NOTE:- Drills not included. TREUNICS