CLA-VAL Co Check Valve. P/N C637501C 81M-EP 3/8IN Size 3/8" MAXPSI 250 SERVICE SWA FFA -400WOG A VALVE PERMITTING FLOW IN ONE DIRECTION ONLY. IT DOES NOT HAVE A STEM, EXCEPT WHEN EQUIPPED WITH A LEVER AND WEIGHT AND HAS NO PRESSURE ADJUSTMENT. IT MAY BE INLINE OR CARTRIDGE (MANIFOLD) DESIGN. CLA-VAL Co.