Have you started to notice issues arising with your vacuum switch generator? If the generator does not shut off, but you continue to have sufficient vacuum within the toilet, it is likely due to a problem with the Dometic Vacuum Tank Switch. Choose the top replacement with this assembly. This Dometic Vacuum Tank Switch is designed to serve as a replacement for accumulator-style (threaded) tanks. All switches come factory preset. Please note that this assembly does not include a cap/ switch cover. The large O-ring that seals the switch flange to the tank is included.