Allows you to bypass your water heater while winterizing and save on antifreeze. This permanently installed system saves you time and money every year. Sturdy brass backflow preventer and 100% shut-off valve lets you by-pass the water heater with a single turn. Once permanently installed, this kit allows you to bypass your water heater instantly with the turn of a single valve. Easy to install, and designed to last the life of your RV.