12" Steel Ruler + Millimeter Conversion This is a new stainless steel ruler Has a conversion chart on the back that converts inches to millimeters, tap drills and w.w. unf Measures in centimeters and inches Graduated in 1/2 mm increments up to 10 cm and 1 mm increments from 10 to 30 cm Graduated in 1/32" increments up to 3", 1/64" increments from 3" to 4" and 1/16" increments from 4" to 12"