first of all it' s a compass for geologists, it can measure the incline and direction of strata (layers in rocks)
second it's a precision instrument, with unsurpassed quality
third, we have no other idea why it's so ffing expensive, all we know is that our prof wanted us to get these babies so i looked around and found a good deal on one :)
so i got it with money from the university, epic win !
(for reference, we usually use 70$ compasses for the same job, they might be a bit more complicated to work with, but they get things done just as well .....)