Featuring a jar-top bonnet for easy access to diaphragm for quick maintenance inspections, this automatic valve has built-in backflow prevention. The built-in prevention is designed to protect drinking and other household water from contamination. The Lawn Genie 3/4 In. anti-siphon valve also features flow control and both internal and external bleed. Flow control allows for fine tuning of the amount of water pressure going to each individual zone reducing misting and fogging at the sprinkler and therefore saving water. Internal bleed is used to turn the valve on at the manifold location for system check-ups or for extra watering. External bleed is the best way to flush out dirt from the supply and lateral lines during new installations and repairs so dirt can pass through the valve rather than becoming stuck in the valve.