Orbit 57623 Sprinkler System 3/4-Inch FPT Anti-Siphon Valve Anti-Siphon - Prevents contaminates from entering household water supply Flow Control Adjustment - Reduces sprinkler fogging and overspray Internal Bleed Lever -Ideal for testing and flushing sprinkler lines Flow adjustment from 0  8 GPM Heavy-duty Construction and UV-resistant - Provides years of reliable service