Metric.
Used to produce a close tolerance surface finish in taper holes to allow the fitting of hardened and ground taper pins in the building of jigs, fixtures and dies. Manufactured to BS 328 : Part 4 : 1990 and DIN 9A.

METRIC TOLERANCES:
Diameter: Over 1.50 ~ up to 5.00. Tolerance: +0.075, -0.000.
Diameter: Over 5.00 ~ up to 20.00. Tolerance: +0.125, -0.000.