Jan, I actually know one of those two people who manufacture those, met him years ago when he was just getting started. He came into my shop with a carburetor problem and I had a Mercedes Speedometer on the counter I was getting ready to ship to VDO for repairs. He was telling me about making the little gears for some of the problematic ones. At that time he was working at NASA Langley Research Center.
Their quality is outstanding along with the instructions. I rebuilt the 1989 one I was planning on using, then scored a pristine 1989 analog cluster.