You reach to get a caliper when you require measuring. If you can not read it 13, however, a true measurement is meaningless. This caliper takes a vital instrument to the 21st century using an additional LCD digital readout for precise internal and external measurements accurate to .001-Inch. Instantly converts from Metric or SAE, the screen can be zeroed at any given stage on the slide. Place and mechanism lock for alteration that is certain. Hardened steel shaft precision ground jaws. On-off change with auto-off, two long-life batteries contained (one spare).