Material: stainless steel Measure range: 25-2000um(1-80 mils) External diameter: 90mm(3.5inch) For measuring wet film thickness of paints, enamels, laquers, adhesive and many other wet coating that are sprayed, dipped or brushed on a smooth surface.Material: stainless steelMeasure range: 25-2000um(1-80 mils)External diameter: 90mm(3.5inch) Aluminum film thickness gauge