Royal Canadian Air Force service dress tunic button by J.R. Gaunt & Sons of London. Developed by escape and evasion genius Christopher Clayton Hutton at MI9, this looks like a standard 18mm diameter pocket sized brass button but the back can be unscrewed to reveal a carefully concealed 0.25" compass. This example has a reverse thread (unscrews when turned to the right). Virtually undetectable in normal use with an incredibly fine thread these buttons really are a work of art. The compass housed within is half the size of a standard 0.5" escape and evasion compass. The rear attachment loop on the button is slighty bent otherwise in very good used condition. A superb rare item. Stock code E23367.