Stainless Steel Flexible Ruler for Jewelry Making - SFC Tools - 35-510 Flexiblestainless steel ruler measures inches and centimeters on one side, and has a conversion table on the reverse side. Precise to 1/2 millimeters across one edge and 1/32" on the other edge. Conversion table converts between fractions of inches and millimeters, and also has tables for tap drills and W.W. UNF thread size.