A caliper has two jaws, one fixed, the other sliding. Move the sliding jaw by pressing your thumb on the bump on the bottom. Many calipers also have a knurled wheel that makes moving the jaw easier. This sort of calipers come with no line graduated measuring scale, on the caliper there are four jaws two upper and two lower. This electronic measurement as three buttons on the digital caliper On/Off in one buttons you use turn on or off, Zero prepare to take a measurement and the MM/IN also one button if you need it in metric on in inches, the locking screw is to keep the reading in place when you're done measuring and you don’t want to lose the reading located on top of the caliper. The display is turned on with the on/off button. caliper manufacturers china is the most reliable caliper suppliers in the world. The external jaws should then be brought together until they touch and the zero button should be pressed. The digital caliper can then be used to measure distances. Always go through this procedure when turning on the display for the first time. Your caliper can take four kinds of readings: outside, inside, depth, and step. Any caliper, whether it is a vernier caliper, dial caliper, or electronic digital caliper, can take these measurements. Let’s take a look at how you take each of those readings.