1800 SAM SERIES 4", 6" & 12". Ideal for use in areas with changing elevations, the 1800 SAM Series offers all 1800 features plus: Built in Seal-A-Matic (SAM) check valve. Eliminates the need for under-the-head check valves. Traps water in lateral pipes in elevations changes of up to 14 feet. Reduces wear on system components by minimizing water hammer during start-up. Even stronger retract spring to accomodate elevation changes up to 14 feet. Designed for use with all Rain Bird plastic and brass spray head nozzles. "SAM" stamped on cap for easy ID and maintenance. Spacing: 3 to 20 feet. Pressure 25 to 70 psi. SAM capability: holds up to 14 feet of head; 6psi. Flow-by: 0 at 8psi or greater; 0.10gpm otherwise. SAM operable only when installed by bottom inlet. RAIN BIRD 1804SAM 4" Rain Bird 1804 pop-up sprinkler less nozzle, with SAM check valve. 1/2" fpt inlet. sold by each. 75 per case. 1804SAM$2.92 RAIN BIRD 1806SAM 6" Rain Bird 1806 pop-up sprinkler less nozzle, with SAM check Valve. 1/2" fpt inlet. sold by each. 50 per case. 1806SAM$7.71