Origin-8's Ultim8 Single Speed Cassette Cog lets you have your ride any way you like it. This handy cog is dual use — a single speed cog that fits over a Shimano/SRAM freehub body or a fixed cog that bolts on in place of a 6-bolt brake rotor. A wide, zero-flex base design made of forged chromoly steel provides instant power transfer. Enjoy the Ultim8 ride whichever way you like it.