Check the listing for details. Watts 1/2" Manual Backflow System (B1156F and 9D-M3). Condition: Used. Listed at 50.00 USD. The Watts 1/2" Manual Backflow System (B1156F and 9D-M3) is a reliable and efficient solution for preventing backflow in water systems. This unit features a manual valve operation, making it easy to use and maintain. With a reduced pressure zone (RPZ) backflow preventer type, this system ensures that the water flow is protected from potential contamination. Designed for use with 1/2 inch pipes, this unit is suitable for various industrial and commercial applications. The Watts brand is known for its quality and durability, making this backflow system a trusted choice for keeping water systems clean and safe.