Mechanical room hygrostat HYGRASREG® RH - 2 with switching output (with single-pole microswitch, as two-position controller with humidity sensor), operates without an external voltage, with humidity measuring element made of stabilized synthetic gauze, with optional setpoint setter for switchpoint adjustment (external or internal setting) in an elegant enclosure made of plastic, with snap-on lid, base with 4-hole attachment for installation on vertically or horizontally installed in-wall flush boxes, with predetermined breaking point for on-wall cable entry. The RH - 2 is used for controlling and monitoring the relative humidity in office and residential rooms, baths, labs, control cabinets, computer rooms, etc., as minimum or maximum hygrostat. It is used in dust-free, unpolluted, non-aggressive air.