Inch.
Sherwood Taper Pin hand reamers are 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.

INCH TOLERANCES:
Diameter: Over 1/16" ~ up to 7/32". Tolerance: +0.0003, -0.0000.
Diameter: Over 7/32" ~ up to 7/8". Tolerance: +0.0005, -0.0000.