These fittings allow you to attach custom fuel lines to the factory fuel rails. They have a Ford spring lock fitting on one end to attach to the fuel rail, and a male AN fitting on the other. The male fitting will thread onto a female fitting on the end of braided stainless or push-lok fuel hose.
The factory fuel feed line is only 5/16 Outside Diameter. On the inside it is only around 0.23 inches. (These figures are for a 86-98 return style fuel system) Fuel flow to the rails can be significantly improved by replacing the small factory feed line with a AN-8 (1/2") or even AN-6 (3/8") line.
Some restriction will remain from the small ID if the inlet tube on the fuel rail itself, but the majority of the restriction will be eliminated by replacing the feed lines. (The original Steeda Outlaw car that won the championship back in 1993 had a similar setup)
Fuel hoses and adapter fittings for the fuel pump & filter not included.