3/4" NPT Inlet/Outlet Adaptor Aluminum Fits AD Filters Only with a 3.70 diameter 1.5-16 UNF 1" Flow (Aluminum) PetroClear Aluminum Heads are epoxy impregnated. (Fits AD filters only with a 3.70" diameter) APPLICATION: 40502/5/10/30, P-AD, 40510 A-AD, 40510 D-AD, 40510/30 W-AD, 40910/30 P-AD, 40910/30 W-AD