PORTS AND FITTINGS
The fuel rail ports are tapped for 8AN ORB.
Appropriate fittings must be selected based on the specific application. Ample space around the fuel rail port(s) is necessary for larger accessories such as fuel pressure regulators, fuel pressure gauges, and fuel pulse dampers. To verify clearance, the dimensional drawings on the product pages can be used as a reference guide.
The Radium Engineering high flow secondary fuel rail is for the 13B-RE rotary engine originally found in the 1990-1995 Mazda/Eunos Cosmo. The aluminum fuel rail is anodized black for compatibility with all popular fuel types including E85. Manufactured with a large internal bore, the fuel rail can support all necessary engine power requirements. Like the stock fuel rail, the rail features 11mm injector bores permitting the use of OEM fuel injectors (shown below). 
The three 8AN ORB ports are compatible with these fittings HERE. The extra center port allows additional fuel system accessories such as the OEM fuel temperature sensor (using 14-0421 shown below), a pressure transducer, Radium fuel pulse damper (shown above), etc.
Thermal insulating spacers and washers are included with stainless steel hardware to prevent thermal energy from conducting heat into the fuel.
The included 14mm lower injector seats were designed specifically to be compatible with or without the OEM diffusers in place. They feature FKM O-rings making them suitable for boosted applications.
FUEL INJECTOR COMPATIBILITY
When the included insulating spacers and injector seats are NOT installed:
OEM Mazda Top Feed Fuel Injectors
When the included insulating spacers and injector seats are installed:
Injector Dynamics ID1050-60-11-14
Injector Dynamics ID1300-60-11-14
Injector Dynamics ID1700-60-11-14
Injector Dynamics ID2000-60-11-14
Injector Dynamics ID2600-60-11-14