The Checkline DM-830-1-A Analog Metric Dial Thickness Gauge, Range 0 - 50 mm, Jaw Depth 300 mm, Feeler A (6 mm) for Rigid Leather, Glass, Sheet Metal 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.