The strut mount secures the strut to the chassis of your BMW. Over the course of tens of thousands of miles this mount can wear out or fail. When replacing strut assemblies we also recommend replacing the strut mounts even if they are in good condition. This ensures long service life of your suspension. **Note:** The holes for the mounting bolts are not threaded. The mounting bolts are self tapping and will cut threads into the mount. You do not need to thread the holes prior to installation.