Make your wheels interchangeable with the use of just one tool. The Raven Hub system can be incorporated into any bicycle set-up. With just the change of end caps (sold separately), the Raven hub can be 130mm, 135mm, or 12x142. It can also be incorporated into either a rim or disc braking set up. The Raven Hub System Package includes two outer shells made to be laced up on any rear wheel, an inner shell and freehub body to hold your desired cassette, dual lock rings, and lock ring tool to lock the system into place. Additional outer shells sold separately.