The Trend CB Counterbore is extensively used for recessing bolt and screw heads and is supplied with a HSS slow spiral drill bit. Fully adjustable, a hex key is supplied. The TCT version is used for plywood, particle boards and plastics (abrasive). To be used at drilling speeds only, they are not suitable for ferrous and non-ferrous metals. When setting up, ensure the flutes of the drill are aligned with the flute of the counterbore. For replacement twist drills, use slow spiral type e.g., 501/532 to 501/012. D 9.5mm. D2 3.96mm. OL 75mm.