Wet Film Comb 25-3000 µm Hexagonal Gauge Stainless Steel Thickness gauge and storage case. These hexagonal precision formed stainless steel wet film combs are long lasting and reusable and are supplied in a range of thicknesses measuring up to 3000µm (120mils).Six sided combs give 36 measurement steps providing increased accuracy. Directions on using a wet film comb: Place a comb perpendicular to and touching the substrate. Hold the comb in position and wait a few seconds until the teeth are wet. Remove the comb from the film. The wet film thickness lies between the biggest value 'coated' or 'wet' tooth and the smallest value 'uncoated' or 'dry' tooth.