Dynalon 312635 Water Jet/Faucet Aspirator Vacuum Pump Water flow-powered vacuum pump for siphoning liquid or evacuating gas in a variety of applications Water supply connects to R3/4 or R1/2 threaded hose fitting, or to a 10 to 12mm inside diameter (ID) flexible tube, requires 3.5 bar minimum supply pressure Siphon connects to 6 to 9mm ID flexible tube and generates up to 16mbar vacuum Anti-backflow check valve for safety Polypropylene (PP) pump and fittings and fluoroelastomer (FKM) and polytetrafluoroethylene (PTFE) check valve for chemical resistance and durability