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 produce pilot holes only.
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