Width Across Flats Normal Tolerance Over (mm) Up to incl. (mm) Plus & Minus (mm) Plus Nil - Minus (mm) 4.0 10.0 0.10 0.08 10.0 20.0 0.20 0.10 20.0 30.0 0.25 0.13 30.0 40.0 0.30 0.15 40.0 50.0 0.40 0.20 50.0 70.0 0.50 0.25 70.0 100.0 2.00% + 1.5% - 1.5% 100.0 3.00% + 2.0% -2.0%