Checkline JD-50R [JD-50R] Digital Thickness Gauge with Rollers and Flange, Range 0 – 12.5 mm / 0.5 inch, Depth of jaw 50 mm / 2". Measuring Ranges: 0 - 0.500" / 0 – 12.50 mm, Resolution: 0.001", 0.01 mm, Jaw Depth: 50mm / 2". The JD-50R 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.