Here is a WWII-era Sensitive Altimeter AN-5760-T2A made by Conn. It has a serial number prefix of AF45, evidence of a year of manufacture of 1945. The Sensitive Altimeter displayed altitude using 3 pointers. The first and longest indicated 100's of feet, the second indicated 1000's of feet, along the outer scale, and the third and smallest indicated 10,000's of feet. on the inner scale. The knob is used to adjust the altimeter to the barometric pressure as displayed in the small window at the 3 o'clock position. It is clearly experienced but in exceptional condition given its age. The knob rotates, but it clearly is out of calibration since that was not the altitude at which these photos were taken. Measures 3.25 inches diameter and ~4 inches deep.