THE REGULAR DRIVER THAT FITS ALL ODYSSEY CASSETTE HUBS. THE DRIVER INCLUDES THE DRIVER BEARINGS, THE PAWLS AND SPRING, AND THE COG LOCK RING. IT DOES NOT INCLUDE THE COG ITSELF. THIS IS THE DRIVER YOU NEED WHEN YOU PLAN TO BE ABLE TO SWITCH YOUR COGS WITHOUT SWITCHING THE DRIVER. THIS DRIVER WILL FIT 12T - 16T COGS.