At end of the 1 / 2 inch check valves there is a fine mesh stainless steel filter that prevents dirt and particles from entering the water supply and prevents the liquid in pipe from flowings back into the water supply : our filter check valves is connect to pipes and hoses by external thread, just a few turn to tighten our check valves Wide applications: Our check valves water is suitable for water suction pipes, pumps, fountains, washing machines and garden sprinklers and ensures comfort This valves set is, resistant to highly temperatures and highly pressure and has good rust protections Our check valves is brass and stainless steels, which can unnecessary backflow, Manufacturer: Tsophreniq