The NVM/... and NEM/... level controllers are fitted with a float and a float rod to which a magnet is attached to the opposite end from the float. The float follows the level of the liquid and moves the float rod inserted through the screwin threaded nipple of the unit up or down. Above the nipple a guide tube is attached for the floatrod and the magnet, and adjustable magnetic switches are mounted on the outside of the tube. These magnetic switches have so called bistable characteristics; i.e. they remain in the switching status caused by the influence of the passing magnet and only switch over when the magnet passes by in the opposite direction.