Genuine BMW OEM Underbody Chassis Brace M140 M135 and all F20, F21, F22 chassis vehicles
The underbrace improves the handling of your 1 series, makes the car feel much more connected and get rid of the 'floaty' feeling you sometimes feel during hard acceleration.
Cheap modification to improve the handling, and easy to install!
They were really only installed on the 3 door M135i. A few F22 had them, but on the whole, it was a part that just seemed to have been “forgotten” no one really knows why. Maybe it saved money, maybe weight but overall one of the best modifications that you can do.