0.4-0.9mm thick Blade Micrometer 25-50mm Range: 0-25mm 25-50mm, High Accuracy Top quality Blade micrometer The anvil and the spindle have a blade for measuring the groove diameter of shafts, keyways, and other hard-to-reach portions With ratchet stop for constant force With a standard bar Type: External Micrometer Anvil Tip Type: Blade Spindle Tip Type: Blade Display Type: Vernier Supplied in fitted plastic case Thickness of blade: 0.4-0.9mm Manufacturer: ROK international Industry Co., Limited Brand: ROKTOOLS To read a micrometer, you need to understand its parts, particularly the thimble and the sleeve. The sleeve has markings showing an inch divided into quarter parts. The thimble rotates around the sleeve, reading the correct measurements. You can practice how to read a micrometer by following instructions you can find online