Checkline DM-820-1 [DM-820-1-F] Analog Metric Dial Thickness Gauge, Range 0 - 50 mm, Jaw Depth 200 mm, Feeler F (3.5 mm) For Sheet Metal, Glass, Round Material. Measuring Range: 0 - 50 mm, Resolution: 0.1 mm, Jaw Depth: 200 mm. The Checkline DM-820-1 Analog Metric Dial Thickness Gauge is used 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.