2" NPT Inlet/Outlet Adaptor Aluminum 4 bolt flange or 1.5" Inlet/Outlet Fits Non-AD with a 5.00 diameter 1.5" 16 UNF 1" Flow (Aluminum) PetroClear Aluminum Heads are epoxy impregnated. APPLICATION: 50710P, 50710W, 51110/30P, 51110/30W, 51110A