The Checkline DM-840-F Analog Metric Dial Thickness Gauge, Range 0 - 100 mm, Jaw Depth 400 mm, Feeler F (3.5 mm) for Sheet Metal, Glass, Round Material 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.