These American made belt pulleys fit Twin Cam with the OEM 6-speed transmission, such as 2006-2017 Dyna, 2007-2017 Softail and 2007-2016 Touring. The pulley with 30 teeth increases acceleration, the 34 teeth pulley will reduce engine speed with 180RPM at 60MPH (96km/h). 34 Tooth pulley does not fit 2014-2016Touring.