Compass, Aperiodic, US Army Air Force Type D-12 Victor See diagram from the UH-1

See diagram from the UH-1 Flight Manual

The knurled center knob was then tightened to secure it in place

or Sacramento Air Material Area at McClellan Air Base

according to their flight manuals from the 1950's

Compass, Aperiodic, US Army Air Force Type D-12 Victor See diagram from the UH-1The 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 45, indicative of a manufacturing year 1945. The navigators' direct reading compass is known as an aperiodic (without a period) compass, since