Bomb Sight, Course Setting, Mk IXA British RAF 1940, "Wimperis"

The Course Setting Bomb Sight, Mk IXA, was used in British RAF and Royal Navy and RCAF bombers during WW2, such as the Short Stirling and Avro Lancaster.  It is a near complete kit - the drawer in the wooden case contains the metal scales with different ranges of True Air Speed and Altitude which were planned for the bombing run.  These had to be selected and installed on the sight well before the final approach.  This particular sight has a serial number which indicates its date of manufacture: 1940.  Wikipedia has a comprehensive description and history of the Course Setting Sight.  A pdf file of the manual is available at the website of the Canadian Museum of Flight.