The Valterra T81 RV Sewer Rotating Valve combines rotating black water and gray water waste valves. 3" hub slides over black water line. 1-1/2" hub slides over gray water line. 3" spigot slides into a separate sewer line. Please note: Paddle is slightly smaller than opening to ease opening/closing. Valve seals cover any gaps and ensure no leaks. 1-1/2"" hub slides over gray water line 3"" spigot slides into a separate sewer line | Valterra Ell Double Rotating Valve, 3" Hub x 1-1/2" Hub x 3" Spigot Outlet in Black