Marineland Magnum Quick Disconnect Double Valve 5/8" 1 pk (PA0588) Double stopcock water tight valve with quick disconnect is installed just above the filter to regulate flow Allow to seal off hoses so one can clean filter without spilling water Double valve stops water flow from both aquarium and canister filter To shut off and disconnect both lines in both directions 2 double disconnect valves needed Measures 5/8-inch size