ISO 3294:2016 specifies the dimensions of parallel shank countersinks for angles 60°, 90° and 120° inclusive.

It specifies dimensions in metric units only, these being regarded as the only recommended dimensions in the future, for countersinks with cutting diameters in the range 8 mm to 25 mm.

The dimensions apply only to tools made from high-speed steel. However, if the method of production allows, the shanks may be manufactured from a suitable alternative material, such as a carbon steel.

Unless otherwise indicated, the countersinks will be right-hand cutting.

Morse taper shank countersinks are the subject of ISO 3293.