RAF service dress tunic button by Buttons Ltd. of Birmingham. Developed by escape and evasion genius Christopher Clayton Hutton at MI9, this looks like a standard brass button but the back can be unscrewed to reveal a carefully concealed 0.5" 'four-hole' rotor compass. Virtually undetectable in normal use with an incredibly fine thread these buttons really are a work of art. The compass housed within is not a standard 0.5" escape and evasion compass but is actually significantly shallower to allow a better fit. Beware of fakes on the market with coarse threads and fitted with standard 0.5" compasses. The compass rotor 'sticks' occasionally but generally in very good condition. Guaranteed orignal. Stock code E22437.