Here is an early WWII-era Sensitive Altimeter, Air Corps US Army Type C-12, made by Kollsman, part number 671-BK-010. The C-12 Altimeter was used across all aircraft of the 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. It has a serial number prefix AF-43, evidence of a manufacturing year 1943. The C-12 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 is just peaking from behind the 1000's pointer. The knob is used to adjust the altimeter to the barometric pressure as displayed in the small window at the 3 o'clock position. This is untested and there is no guarantee made to its' function.
The knob does move the dial.