The thickness of any substrate can be measured under a specific contact pressure using this Caliper Gauge D2R20. It can also measure the inner and outer diameters of any object. This is a mechanical internal measuring gauge with a measuring range of 0-20mm, a scale interval of 0.01 mm and a measuring depth of 85mm. It is widely used in the measurement of tube wall thickness. One measuring contact is fixed while the other is movable. It is supplied in a wooden box.