PresAir Trol Tinytrol Pressure Switch [21A] [1 8" MPT] [SPDT] [2 PSI] (TNP 111R 2PR) fuses A lid is useful because A lid is useful because it helps close and protect the chlorinator chamber while still allowing access for chemical refills and routine maintenance work this replacement control helps support dependable multi pump spa operation and contributes to more stable overall system performance The PresAir Trol TinyTrol pressure switch is built for compatible systems that use a 1 8 inch MPT connection and need an SPDT switch rated at 21 amps with a 2 PSI operating point This model is especially valuable when the original switch no longer reacts accurately