Surly Single Speed Cogs. Features: Designed as a singlespeed cog, but may also be stacked and used with 9-speed shifter. Multi gear use will result in slower, less crisp shifting than cogs designed for multi-gear systems Fit Shimano freehub splines SCM 415 hardened chromoly steel Photo for color and material reference only Specs: MaterialSteel Tooth Count22 Drivetrain SpeedsSingle Speed 3/32" Cassette Body TypeShimano 7 Speed