german luftwaffe compass?

[conker]

hi guys i would like to find out more about this item before i put it in the sale section ive been told its a german luftwaffe pilots compass any furthur info type date etc greatly appreciated manythanks also there is a liquid inside the compass also the under side goes clear when the top is twisted for reading maps i think??

ive just found this link here from another forum member from 2006 and its this one i have without the box identical

any more info would be great and an idea on value there 1 for sale on ebay buy it now for ?256 is this a fair market price the item number 120219554995 ive searched the internet and cant find another for sale anywere