Rain Bird 1806-SAM 6" Pop-up Sprinkler Spray Head w/Seal-A-Matic Check Valve Built-in Seal-A-Matic (SAM) check valve: Eliminates need for under-the-head check valves No parts to be installed at the site Traps water in lateral pipes in elevation changes of up to 14 feet (4,2 m) Reduces wear on system components by minimizing water hammer during start-up Prevents drainage from spray heads at lower elevations Stops water waste Ends landscape damage due to flooding and/or erosion SAM stamped on cap for easy identification and maintenance Designed for use with all Rain Bird p