Take depth measurements in dirty machining environments. These micrometers are rated IP65, so they seal out oil, water, and dust. They come with multiple extension rods that you can swap out depending on the depth of your holes, slots, shoulders, or projections. They have a ratchet-stop thimble with a speeder knob to reduce the time it takes to open and close the micrometer. For repeatable measurements, the thimble stops turning once the spindle reaches your part to prevent overtightening. However, the speeder knob will continue to turn with a clicking sound. These micrometers have zero-position memory, also known as absolute (ABS) positioning, so they retain the measuring position after you turn the micrometer off. A zero-set button lets you start measuring at any point.