The 154138 filter housing cap has 3/4" inch NPT inlet and outlet ports. The 154138 housing top has a red pressure release button that can be used for optional pressure relief or bleed. The 154138 housing cap includes a Valve In Head for easy water shut off. External shut-off valves are not needed. The 3/4" inlet/outlet filter housing cap is made of reinforced polypropylene. The 154138 water filter housing cap fits #10 Standard Clear water filter housings.