This billet 6061 aluminum adapter fitting allows an OEM fuel pressure regulator to be reused in an application other than the OEM fuel rail. It is compatible with most Nissan engines including SR20DET, KA24DE, etc. It features 3/8 Inch NPT male threads with a bright dipped Type-II green anodized surface finish. Each end of the adapter mimics the profile of an 11/16" (18mm) wrench for rotating during installation.Some OEM Nissan FPRs use M5 screws. If this is the case, you simply use a 1/4 Inch bit to drill out the 2 OEM FPR flange holes larger. The OEM FPR will be secured to this billet FPR adapter using the included stainless steel M6x1X14mm socket head bolts.