Motorworks.
The rear one is the standard fit to the R1100 final drive.
The front one is from one of the BMW bikes, but which one escapes me, it was a long time ago. Might be the front one for the R1100. Anyway the one I got was too large for the R1150 swinging arm, so it needed to be shortened.
I just cut it down to the required length. The end fittings are spot welded to the band with 2 small spot welds. I just drilled two small holes where the welds were on one of the end fittings, cut the band to the required length. drilled 2 small holes in the band and riveted it back together. It's a bit fiddly, and requires a bit of thought. I chose to rivet it because at the time, it was the easiest solution.
Edit
They are both from the R1100GS
Rear = diameter of 90mm part no 33171458197
Front = diameter of 132mm part no 33172335120