The room hygrostat is designed to monitor and regulate the relative humidity, e.g. in business premises, apartments, conservatories, bathrooms, swimming pools, computer rooms and other rooms with a clean, non-aggressive environment. The effect of the relative humidity on a measuring tape activates a potential-free changeover contact. The setpoint is set using the setting button on the front. The setting range can be restricted. Can be adapted to almost all surface switch programs with a cover set 50 x 50 mm or 55 x 55 mm. Suitable cover set no. JZ-021.xxx.