ISO 3293:1975

Morse taper shank countersinks for angles 60 degrees, 90 degrees and 120 degrees inclusive

Specifies only the metric dimensions of these countersinks. Metric dimensions being regarded as the only recommended dimensions in the future, for these countersinks with diameters in the range 16 to 80 mm. The dimensions given apply only to tools made from high speed steel or a suitable carbon steel. These countersinks will be usually rigth-hand cutting.