The KOBOLD level switches »RFS« are designed for monitoring filling levels of liquids cost-effectively. The liquid must not contain solids nor metallic particles. A pivoted stainless steel float with an inserted solenoid moves up and down together with the filling level of the liquid. The solenoid switches a reed contact. Depending on the mounting position of the device, the contact works as NO or NC contact with rising filling level. The devices are delivered for direct lateral mounting in commercially available sleeves.