This deluxe digital caliper comes standard with a stone holding plate attachment for easy measuring of loose stones, watch crystals, beads and more. With the touch of a button, you can convert measurements from millimeters to inches and back. Accuracy to .01mm. The measuring system is a non-contact linear CAP with LCD display and an auto-off system to save the battery. Caliper will measure inside, outside and depth. Features a fine adjustment thumb wheel and zero set button. Comes in a protective nylon carrying case with foam padding and one spare battery. Maximum opening 6".