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).