The FBI (Frame Bearing Interchange) skate frame is a type of inline skate frame that allows for easy swapping of wheels and bearings. This feature allows skaters to quickly change wheel setups for different skating styles or environments. The FBI frame uses a standard 608 bearing, which is the most common bearing size in inline skating. This allows for interchangeability between brands and ensures easy access to replacement bearings. The FBI system is popular among recreational skaters and fitness skaters who want the convenience of quickly changing their wheel setup.