A five piece set of 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 & are self clearing. They are adjustable for different length screws & will produce a 9.5 mm. (3/8 in.) or 12.7 mm. (1/2 in.) diameter counterbored hole to fit standard wood plugs. Contents. 2.0 mm. (5/64 in.) Drill & C/S Size No. 4. 2.4 mm. (3/32 in.) Drill & C/S Size No. 6. 2.8 mm. (7/) Drill & C/S Size. No. 8. 3.2 mm. (1/8 in.) Drill & C/S Size. No. 10. 3.6 mm. (9/) Drill & C/S Size. No. 12.