oh hey, its a Mikrokator
been a while since i've seen one of those. used to use those a lot back at PI boring holes to +/- 5 millions. very accurate measuring tool.
that isn't a good measurement of plannarity though. the real way he is getting them flat is though the use of the 3 plate technique pioneered by Moore. have i ever mentioned before that everyone who ever wants to do anything mechanical needs to read his book? i think i've only suggested it 100 times ...