Measuring Range: 0.4 inch / 0 - 10 mm, Resolution: 0.001 inch / 0.01 mm, 2" (50 mm) Jaw Depth. The Checkline JD-500 digital thickness gauge features an easy to read LCD display along with the high accuracy. The user can select to display thickness in inches or mm. The JD-500 model is available with 5 different feelers, which can be found below. Measurement is done by a spring force. Opening by lifting device (lever) - self closing.