RCBS' Electronic Digital Caliper switches from inches to millimeters with the touch of a button. It ranges from 0-6-inch/0-150mm with +/- 0.001-inch/0.02mm accuracy. Resolution: 0.0005-inch/0.01mm. The caliper features large, easy to read numbers which helps reduces error on guessing. It also measures internal, external, depth and step dimensions. Jaw depth measures 1-1/2-inch outside, 5/8-inch inside. Lock holds slide in position for measuring constants. Battery included. Low battery indicator. Fitted plastic storage case.