These adapter fittings are designed to be used in many Radium products including fuel rails, surge tanks, fuel pressure regulators, etc. However, they can be used in any application using a -8AN ORB (3/4"-16) O-ring port.

20-0301,2,3 (example shown below) are used to adapt to OEM components, such as fuel pressure regulators, fuel pressure sensors, etc.  More information about these FPR adapters can be found here:

 
Below is an example of the 8AN ORB swivel banjo to 6AN fitting.
 
Below is an example of the 8AN ORB swivel banjo to barb fitting.