Heat treated tool steel countersinks with a HSS drill.
Adjustable for different length screws and can produce a 9.5mm (3/8 inch) diameter or 12.7 mm (1/2 inch diameter counterbored hole for woodplugs.
The drill produces pilot holes only.

Specification:
Shank Diameter=1/4 inch hex
Softwood=No.6 to No.12
Hardwood=No.4 to No.10
Drill dia.=2mm to 3.5 mm
Countersink dia.=9.5 mm & 12.7 mm

Includes:
1 x 2.0mm (5/64") drill countersink
1 x 2.5mm (3/32") drill countersink
1 x 2.75mm (7/64") drill countersink
1 x 3.25mm (1/8") drill countersink
1 x 3.5mm (9/64") drill countersink