This is a Genuine BMW part developed to prevent the common problem of front strut housing deformation. This problem can be found on completely stock street cars. Age, metal fatigue, and bad roads all combine to deform the thin sheet metal of the upper strut towers. Adding performance-oriented suspension and driving on track further increases the chance of damage to the car.
We regularly find donor cars with deformed strut towers. We typically repair the damage and install these reinforcement plates. For those lucky enough to not have any existing damage, these plates are a great preventative measure.
We normally weld these in place with a few short welds evenly placed around the outer edge, but welding is not absolutely required. They can simply be sandwiched between your strut top hat or camber plate and the strut tower.
Fits all E46 models.