Vernier Digital Gauge With a small locking thumb screw which locks the jaws in place. 1 x Digital Gauge. Zero setting in any position. This instrument is Four Spot On Gauges – Internal, external, step and depth dimensions can be accurately measured in real time instead of guesstimating/eyeballing where the lines on the Vernier scale. Easy To Use – There are 3 button on it, one is on / off, one is mm / inch switch, the last is back to zero. You can slide it to anywhere and reset it to zero by zero button. The electronic micrometer Gauge has a large screen for you to read the result.