This is one of the handiest gadgets I've added to my shop in quite some time. The spring-loaded arms allow you to quickly and accurately gauge material thickness up to 1-1/16" as you're sorting lumber, thickness planing, etc.

The compact size (the body is less than 2" across) neatly fits in an apron pocket so it's always at hand, and it's faster to operate that a set of calipers. And if you're not dragging your $100 calipers all over the shop, there's no chance of knocking those calipers onto the floor. Stout spring-loaded arms connect to a metal chassis with a plastic upper housing... this is a beefy little unit, built much more heavily than you might expect. Measures in decimal inch to 0.001", fractions to 1/64", and millimeters to 0.02mm.