30T. -4 tooth smaller than stock. Smaller motor sprockets increase RPM, at the same speed, for more power and better pull in the same gear. Good solution to overcome the sometimes sluggish feel of the 6-speed cruisedrive transmission. Will eliminate the OEM compensator spring and OEM motor sprocket and will allow you to run with a simple but dependable solid set-up. Note: 30t sprockets are 4 tooth smaller than stock. A custom length primary chain is required. 90t chain required for Dyna and Softail and 84t chain for Touring models. These are not(!) available through MCS. Note: 08-10 Twin Cam models require a 2007 style alternator rotor available as MCS 908086 (OEM 40356-07).