Checkline DMD-820-1 [DMD-820-1-D] Digital Thickness Gauge, Range 0 - 1 in (0 - 25 mm), Jaw Depth 200 mm, Feeler D (5 mm) For Rubber Rings, Round Material. hickness gauge to determine the thickness of leather, textiles, cardboard, felt, rubber, sheet metal, foil, plywood, plastic, etc. Self closing thickness gauge with high accuracy and resolution.