This tool setting gauge is made from die-cast zinc-alluminium alloy & is 19mm thick x 229mm long, reaching past the insert plate to the table, unlike other gauges on the market. It is most useful on a table saw for setting blade or rip fence placement. It has 6mm / 1/4" graduations on one end & 3mm / 1/8" on the other, so you can get from 3-50mm & can be set in 3mm / 1/8" increments. Accurate to an amazing ±0.127mm..