Ensure parts are perfectly straight and square—these gauges detect surface deviations so small the human eye can’t see them. As you slide the lever on these gauges up and down, a dial test indicator moves along the vertical surface of your workpiece, measuring how straight and square it is. Checking for slight angles on machined parts or frames verifies they will align properly and function correctly. You can adjust the squareness of the gauges to fine-tune for differences in temperature and humidity and to maintain precision over years of use. Measure an object for height with the scale along the side of the gauge. The housing is cast iron, so the gauges are stable and stand up to frequent use.