The primary function of the clutch roller weight is to control the engines operating rpm. We offer 4 different grams of rollers which will allow you to mix and match so you can come up with several different combination's in overall weight if you are tuning or setting up your own clutching. The other difference in our clutch rollers is the diameter. Our rollers are a smaller diameter than the stock units which opens up the primary clutch more and allows the belt to drop down in the primary clutch farther so you start off in a lower gear ratio, thus, giving you better acceleration, better throttle response, more pulling power and less belt slippage which means longer belt life. Our rollers also come as a complete assembly So you just have to drop them into place and go. There is no pressing, swapping or changing out existing parts with your stock ones to make these work.