This Cog Fits coaster brake and Internally geared hubs with 3-tab spline pattern drivers. They’re perfect for your bike. The Shimano Nexus and Alfine cogs will work with either 1/8” or 3/32” chains. The Cog Snap Ring is here to attach the driver cog to your internally geared Shimano Nexus and Alfine hubs. It’s available in 21t or 22t options.