The room hygrostat is designed to monitor and regulate relative humidity, for example, in commercial spaces, apartments, conservatories, bathrooms, swimming pools, IT rooms, and other areas with a clean, non-aggressive environment. The relative humidity affects a measuring tape, which activates a potential-free switching contact. The desired value is set using the adjustment knob located on the front. The adjustment range can be limited. It can be adapted with a cover set of 50 x 50 mm or 55 x 55 mm to almost all surface-mounted switch programs. Matching cover set number JZ-021.xxx.