Altimeter, Civilian Cessna

This is a civilian altimeter marked for use in a Cessna aircraft. It is date stamped November 1959.

The knob is used to adjust the altimeter to the barometric pressure is displayed in the small window at the 3 o'clock position.  

The glass and case are intact, and the knob rotates, and the pointers move. Measures 3.25 inches diameter and ~4 inches deep.