• The gauge is made of quality tool steel 11mm (7/16”) wide by 160mm (6.1/4”) long and is accurately tapered throughout its entire length for quick and convenient measuring of slot widths, etc. • one side is graduated from 0.010” to 0.150” in thousandths of an inch and the reverse side from 0.3mm to 4mm in onetwentieth of a mm (0.05mm).