General Tools 146 Fraction Plus Digital Fractional Caliper, Carbon Fiber, 6-Inch 3 UNIVERSAL SYSTEMS OF MEASUREMENT - 3 mode digital display easily switches from inches, millimeters and fractions LIGHTWEIGHT, NON-MARRING - caliper is made of lightweight, non-marring carbon fiber composite DELIVERS ACCURATE READINGS - for inside, outside, depth & step measurements ACCURACY/RESOLUTION - accuracy plus or minus 0.004-Inch which is plus or minus 0.1-Millimeter Resolution 0.0005-inch plus AUTO ON/OFF FEATURE