Altimeter, Non-sensitve, 20,000FT Kollsman 126k-011-5021
This is an early vintage (1930-40's?) aircraft Altimeter made by Kollsman, model 126k-011-5021. This altimeter measures altitude up to 20,000 ft, and is regarded as non-sensitive, i.e., the increments of altitude measurements are large (200 ft) and likely limit its use to non-blind flying.
The center knob adjusts the altimeter for local barometric pressure. As the knob is turned, the face of the dial rotates while the scale on the inset window remains fixed.
It is in reasonable condition given its apparent age. Measures 3.25 inches diameter and ~3 inches deep.