Malida 1/8" Thread Male to 1/4" Tube Elbow Check Valve for RO Reverse Osmosis (Pack of 2) Water Male Elbow Check Valve Applications: Apply to Reverse Osmosis Water System and Housing In Line Filters ETC. RO Water Filters,Light weight, easy to load and unload 1/8" Thread male to 1/4" tube elbow Quick connect.