United Instruments Altimeter, 20,000 feet, Kollsman in mBar, 3 1/8" (80 mm)
Calibrated to 20,000 feet
The Altimeter is designed for use in aircraft to help the pilot determine altitude, the height above a reference point (generally mean sea level). The Altimeter measures existing atmospheric pressure, which varies with altitude. Based on the assumption of Standard Day conditions of temperature and air pressure, the altimeter translates this pressure into a "height-above-sea-level" value, which is indicated on the dial of the instrument in feet.

• Size: Fits into a 3 1/8" (80 mm) instrument hole with cutout for the adjustment knob
• Applicable Specifications: TSO-C10b
• Case Configuration: 3 inch case (Flange type)
• Typical Weight: 13 ounces
• Number of Pointers: 3
• Barometric Setting: 946 to 1050 mb 
• Static Pressure Connection: 1/8-27 ANPT
• Installation: Removable spring nuts and screws