The General Tools 6" Steel Digital Caliper has an extra-large, easy-to-read tri-mode digital display and switches quickly and easily between decimal inches, fractional inches and millimeters at the touch of a button. Made of heavy-duty stainless steel. Displays measurements in fractional inches, decimal inches or millimeters. Inside, outside & step measurements. Auto power off. Power source: "SR44" battery (included). Range: 0 to 6 in. (153mm). Accuracy: ±0.001 in./0.02mm Resolution: 1/64 in./0.0005 in./0.01mm