Universal Rear Diffuser Fins

Universal rear diffuser fins. Approximate dimensions 250mm long x 75mm tall x 30mm wide

The mounting face is flat so it would require a flat section of the underside of your bumper to attach to. Attach using 3M double sided adhesive tape such as the following:  https://amzn.to/3X8NHEs  If you've ever mounted body panels etc with this stuff you will know it will never come off. 

If you require a different size fin just scale it in your slicer.