After a lot of research and struggling to find the right rear rack for the BMW F750gs, I went for this and an M8B top plate together. This rear rack fits perfectly if you have the plastic luggage rack fitted to your bike already, I didn't have the metal one so found it hard to know which was right. For the Sr5129 you take the seat off, remove a few of the existing bolts in the luggage rack and put in new support arms which work with the existing plastic. The parts don't come labelled, and some are for use with different top plates. I just laid everything out and worked through slowly and didn't have any issues. With the M8B top plate combination it looks really good and feels totally solid with my 55 litre top box on. Very happy overall.