Orbit 57604 1-Inch FPT Anti-Siphon Valve with 3/4-Inch Reducer Flow Control-Adjusts amount of flow to sprinklers Anti-Siphon-Prevents contaminants from entering household water supply Universal-Works with residential standard 24 Volt sprinkler systems Manual On/Off Bypass Lever-Ideal for testing and flushing sprinkler lines For outdoor use with cold water only