Checkline JD-100R [JD-100RO] Digital Thickness Gauge with Rollers With Flanges, Range 0 – 12.5 mm / 0.5 inch, Depth Of Jaws 100 mm / 4". Measuring Ranges: 0 - 0.500" / 0 – 12.50 mm, Resolution: 0.001", 0.01 mm, Jaw Depth: 100mm / 4". The JD-100R is a digital thickness gauge with ball-bearing mounted cylindrical rollers. It is ideal for measuring the diameter or thickness of slowly moving wire, filaments, foil, ribbon, narrow fabrics, etc., without stopping manufacturing.