Compass, Aperiodic, US Army Air Force Type D-12 NOS P-61 can interpret them by rotating

can interpret them by rotating the card to match the arm position being observed

Would have been used in ground installations (as opposed to use within aircraft

20233) either the Riedelanlassmotor or the engine itself

The scale is labeled to a value of 2

The gyro rotates

Compass, Aperiodic, US Army Air Force Type D-12 NOS P-61 can interpret them by rotatingThe US Army Air Force Type D 12 Direct Reading Aperiodic Compass was used at the navigators station across many US WWII aircraft, including heavy bombers B 17, B 24, B 29, medium bombers B 25 and B 26, and transports C 46, C 47, and C 54. Made by Bendix, part number 1832 1 A, it has a serial number prefix of AF 43, indicative of a manufacturing year 1943. This compass is New Old Stock and is in an original Douglas Aircraft box (but the serial numbers