Rain Bird DASASVF100 Professional Grade Anti-Siphon Valve with Flow Control, 1" Threaded Female x Female Professional grade 1" anti-siphon valve with flow control; compatible with any standard sprinkler timer Designed for above ground installation, will prevent back flow when properly installed 6" above highest sprinkler head Operates automatically or manually with manual bleed screw Reverse Flow design reduces stress on diaphragm for dependable operation Energy efficient, low power encapsulated solenoid with captured plunger Buna-N diaphragm provides superior performance in harsh water environments Flow Range 0.2 to 40 GPM; for less than 3 GPM flow or Drip applications install a 200 mesh filter before the valve