Depth micrometers take measurements of slots, steps, holes, and projections. They have a spindle that is adjusted by rotating a thimble until the rod/beam contacts the bottom of a hole being measured. When it contacts the bottom of a hole, a reading is shown on the digital display or can be determined manually with graduations along a vernier scale. Depth gauges have a beam that’s fixed to a dial indicator or digital display. The beam has a plunger-style flat or rounded contact point on the end. When the contact point makes contact with the bottom of the hole being measured, a reading is shown on the digital display or dial gauge. Blade-style gauges use different tip shapes with a blade-style scare that is lowered into holes to determine measurements. Rod-style gauges are used with fixed or interchangeable rods. They are lowered into holes to determine measurements.