This is meant for bikes that use a GXP spindle crank (SRAM) in a BB30 frame without the use of adaptors. Enduro Grade 3 silicon nitride ceramic balls riding on cryogenically-treated high carbon chromium alloy races means that friction is minimized and longevity of the BB has been maximized. Silicone VV seals have minimal drag and work well keeping the grease in, and the bad stuff out.