Depth gage - A gauge for measuring the depth of grooves or holes or other concavities Height gauge- The left height gauge has the vernier scale, while the right one is an electronic height gauge with a digital readout. A height gauge is a measuring device used either for determining the height of something, or for repetitious marking of items to be worked on. thickness gage- A gage for measuring the thickness of a sheet of material, the thickness of an object, or the thickness of a coating; examples include penetration-type and backscattering radioactive thickness gages and ultrasonic thickness gages.