Altimeter, Sensitive, Type C-11, 35,000 ft, PN 642K-05-784

Here is a post-WWII-era Sensitive Altimeter, similar to the US Army Type C-11, made by Kollsman.  

The C-11 Sensitive Altimeter displayed altitude using 3 pointers. The knob is used to adjust the altimeter to the barometric pressure is displayed in the small window at the 3 o'clock position.  See spec sheet in the photo gallery.

It is in very good condition given its age. The glass and case are intact, and the knob rotates, and the pointers move. It is not calibrated. Measures 3.25 inches diameter and ~4 inches deep.