Tolerance between the nominal size and the actual diameter: +/- 0.01mm for 1 - 45mm diameter setting rings; +/- 0.0004" for 0.1" - 1.8" diameter setting rings, Cylindricity: 1.0 micrometer for 1 - 45 mm diameter setting rings; 0.00004" for 0.1" - 1.8" diameter setting rings.