Free Air Temperature Indicator, Type C-12 WWII, Air Corps US Army
Here is an electric Free Air Temperature Indicator, US Army Air Corps Type C-12, displaying outside air temperature from -45 to +45 deg C. The C-12 indicator was a 12 volt DC instrument. According to the Maintenance Interchangeability Chart dated Dec 1943, the C-12 was used in training aircraft AT-6 Texan, AT-9 Jeep, BT-12 Sophomore, and BT-13/15 Valiant.
Made by Weston, part number 106498, it is in fine condition given its age. On its face is embossed "AC US ARMY" for Air Corps. See spec sheets in the photo gallery. Measures 2.25 inches diameter and ~3 inches deep.