it's quite a small unit but still to large for BMW original rear spoiler. I almost fin one ought to be looking at some copper tube cut open lengthwise, bend to follow the shape of the rear window and somehow attaches under the rubber of the rear screen, chromed for reflection. and the LEDs place inside. Not easy and a lot to detail work to sort out. I think the spoiler suggestion from Bruce is better. Just that not everybody wants or has a rear spoiler. Best Regards Ralf