US Products FP144 Siphon Plug Pump Priming QD X 2" Used your vacuum on your carpet cleaning machine to suction prime the air liquid though your pump and hose. Needed on US Product extractor when you transition from water to dry cleaner and back to water again. Can be used with any make or brand extractor. Included with new US Products PB3 Ultimate cleaning extractor. The order original item was smaller and fit inside of the 1.5" hose cuff. The new design works with all hose sizes including 1-1/4", 1.5" and 2" hoses.