Description: Easy to install: Excellent upgrade smooth extra power easy spring change. Function:It Was able to tune the clutch depending on what terrain you are riding on. Package includes:Red 30 series spring, 6* wear buttons. Note:If the buttons are slightly too large for the holes of your driven unit. With a little bit of sanding and light tapping from a small hammer they fit right in. Note: Rebuild kit for 30 series driven pulley (Red spring). Most common Torque converter type, note this will not work with a 20 series setup.