Check the listing for details. WATTS 3/8 DUAL CHECK VACUUM BREAKER BACKFLOW PREVENTER. Condition: New – Open box. Listed at 229.00 USD. This WATTS 3/8 Dual Check Vacuum Breaker Backflow Preventer is perfect for anyone in need of a reliable and effective solution to prevent backflow in their plumbing system. Designed for use with water media and a manual valve operation, this backflow preventer is suitable for use in various industries, including business and industrial settings. The brand, WATTS, is known for producing high-quality plumbing products, and this backflow preventer is no exception. With a pipe size of 3/8 in, it is compact and easy to install. This product is an excellent choice for those who want to ensure the safety and health of their water supply by preventing the backflow of potentially contaminated water.