This Digital Electronic #Gauge is made of hardened stainless steel and easy to use. You can use it in both SAE (inch) or Metric (mm) with conversion and set it to zero in any position. The caliper has four measurement types: internal dimension, external dimension, depth and steps. With a large LCD display and a small locking thumb screw you can lock the jaws in place. Also,there is automatic turn-off fuction.