Altimeter, Sensitive, Type C-13, 35,000 ft, US Navy WWII 671K-05
Here is an early WWII-era Sensitive Altimeter, Air Corps US Army Type C-13 (also AN-5760-1), made by Kollsman. part number 671K-05. The C-13 Altimeter was used across all aircraft of the US Navy and Air Corps US Army, including heavy bombers B-17 and B-24, medium bombers, B-25 and B-26, Fighters P-38, P-39, P-40, P-47, and P-51, and transports C-46 and C-47, according to the Maintenance Interchangeability Chart dated Dec 1943. This altimeter is similar in appearance to that shown in the F4U Corsair Flight Manual dated 1944, see photo of instrument panel from its manual.
The C-13 Sensitive Altimeter displayed altitude using 3 pointers. The first and longest indicated 100's of feet, the second indicated 1000's of feet, and the third and smallest indicated 10,000's of feet. The photos shows the first two pointers, and the smallest pointer travels along an inner dial. The knob is used to adjust the altimeter to the barometric pressure as displayed in the small window at the 3 o'clock position. See spec sheet in the photo gallery.
It is clearly experienced but in reasonable condition given its age. The glass and case are intact, and the knob rotates stiffly, changes the barometric display, and the pointers move. Measures 3.25 inches diameter and ~4 inches deep.