16" 500A Swing-Flex® Check Valve 3D-516C 16" 500A Swing-Flex® Check Valve – Backflow Actuator 3D-516CBF 16" 500A Swing-Flex® Check Valve – Backflow Actuator, Mechanical Indicator 3D-516CBFMI 16" 500A Swing-Flex® Check Valve – Mechanical Indicator 3D-516CMI 18" 500A S...