Surly Single Speed Cogs. 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 : Material: Steel Cassette Body Type: Shimano 7 Speed Tooth Count: 13,16,17, 19, 22 Drivetrain Speeds: Single Speed 3/32"