Disc Mount Fixed Sprocket

Sprockets with a 6-bolt hole pattern, just like disc rotors, so you can attach them to hubs with disc rotor mounts for fixed-gear use.

Can also be used with a Cassette Cog Carrier (available separately), which is Shimano-splined and sandwiches a spline-less sprocket. This gives you a wide profile that won't damage your freehub