DeFelsko PosiTest Mode D'emploi page 3

Second: Once the visual indicator remains down: with your
index finger, slowly turn the dial wheel in the opposite direction,
until you hear a click and see the visual indicator pop up.
At this point, read the coating thickness on the scale.
Note: PosiTest is available in two measuring ranges and in
mils or microns scale.
If the majority of your coating measurements are below 3 mils (70 µm):
PosiTest Model GM (G) is most suitable.
If the majority of your coating measurements are above 2 mils (50 µm):
PosiTest Model FM (F) is most suitable.
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