Hygrometer holder

This is a standard-size hygrometer holder, round with a diameter of 41 mm. I've precisely sized the holder for placement in the central section of the AMS system, which will help you accurately monitor the humidity level in the AMS box. I intentionally don't use a hygrometer built into the silica gel box, as many do, as it's the air humidity level that's important, not the moisture content of the silica gel.