BlackMax adjustable primary weights for the Polaris standard p90 clutch found on most models from 2013+. These weights are made out of high carbon machine billet steel. The weights are adjustable using powerful rare earth magnets. If you are someone that likes to tune your clutching to get your machine dialed in perfectly or if you have a custom build setup that needs a custom tailored clutch kit then these weights are what you need. You will be able to add or remove weight to raise or lower the operating RPM of the machine. These weights perform very well!!!