Checkline JD-50 Digital Thickness Gauge, Range 0 - 10 mm, Depth Of Jaw 50mm. Resolution0.01 mm / 0.0005 inch, Measuring range0 - 10 mm / 0.4 inch, Depth of Jaw 50 mm. The JD-50 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-50 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.