Checkline DMD-820-1 [DMD-820-1-F] Digital Thickness Gauge, Range 0 - 1 in (0 - 25 mm), Jaw Depth 200 mm, Feeler F (3.5 mm) For Sheet Metal, Glass, 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.