Instant reading. Very easy to use. Hardened stainless steel body for prolonged tool life. Switches from inches to millimeters with the touch of a button. Range of 0-6-inch/0-150mm. Accuracy +/- 0.001-inch/0.02mm. Resolution: 0.0005-inch/0.01mm. Large, easy to read numbers, reduces error-no guessing. Adjusts to zero at any position. 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.