SPI Electronic Caliper 0-6" / 150 mm Measuring Range 0.001" / 0.1mm Resolution 0.004" / 0.1mm Accuracy 1.57" / 40mm Jaw Length Ultra Light Weight (1.7 oz) for easy handling. Inside, outside, depth and step measuring Super Polymid, 60% fiberglass reinforced plastic of highest quality. Depth rod, frame and housing are made of non-conductive plastic. Resistant to chemicals and corrosion. Large, high contrast LCD display. Zero setting at any position within entire range. Direct inch/mm conversion. Alarm signal for low battery and over speed. 2 year battery life (approx.).