The Trend Countersink Set contains five heat treated tool steel countersinks with hex shafts. They are fitted with High Speed Steel drill bits to cover the full range of screw sizes and are self clearing. They are adjustable for different length screws and will produce a 9.5mm (3/8in) or 12.7mm (1/2in) diameter counterbored hole to fit standard woodplugs. Contains: 1 x 2.0mm (5/64in) Drill and C/S Size No.4.1 x 2.4mm (3/32in) Drill and C/S Size No.6.1 x 2.8mm (7/64in) Drill and C/S Size. No.8.1 x 3.2mm (1/8in) Drill and C/S Size. No.10.1 x 3.6mm (9/64in) Drill and C/S Size. No.12. Tungsten Carbide tipped version , these tools can be used in abrasive materials such as laminated chipboard. The drills produce pilot holes only.