The Surly Splined Cassette Cog is a precision-machined, heat-treated chromoly cog designed for 3/32" chains and compatible with Shimano-style splined freehub bodies. Available in a wide range of tooth counts (13–22T), it's ideal for single-speed conversions or custom setups where durability and drivetrain efficiency are key. The full-profile tooth shape offers smooth engagement and excellent wear resistance.