**Only for use with updated style tension struts, will not work on original tension struts due to difference in ball joint size** Ball joints are a critical piece of your BMW's suspension. They allow for the suspension to articulate as the vehicle travels over the road. With age and high mileage ball joints can easily deteriorate which causes suspension noises as well as play affecting handling performance. FCP recommends replacing ball joints in matched pairs for the best service life and performance.