The KOBOLD flow meters and switches model VKG have a spring-loaded float, which slides within a cylindrical measuring tube and has an integral orifice which is believed to be unique. This and other design features means that it has for the first time become possible to create a flow meter and switch which fully compensates for viscosity and to a large extent for density even with very low flows. The float of these patented devices contain permanent magnets which actuate a potential free bistable reed contact mounted outside the flow thus ensuring hermetic separation between the medium and the electrical contact system. The contact is embedded within a height-adjustable plastic housing to prevent damage to the contacts by mechanical action or aggressive atmospheres.