Altimeter, Mk XVIIA, Ref 6A/1538 0-35,000ft, British Royal Air Force C-121 "triggering" the Eureka (AN/PPN-1) and

"triggering" the Eureka (AN/PPN-1) and causing it to return a pulse

Flange diameter

Here is a WW2-vintage Rate of Climb (Vertical Airspeed) Indicator

This Soviet/Russian aircraft instrument appears to be for setting an airspeed between 70-220 kilometers per hour

For dual-control installations

Altimeter, Mk XVIIA, Ref 6A/1538 0-35,000ft, British Royal Air Force C-121 "triggering" the Eureka (AN/PPN-1) andHere is a British Altimeter Mk XVIIA, Rf 6a 1538 as used in WW2 RAF bombers such as the Avro Lancaster, showing a maximum altitude of 35,000 ft. The altimeter has the marking of ICAN, the International Commission for Air Navigation. ICAN was an international governing body established on the basis of the ICAO relating to the regulation of aerial navigation and dealt exclusively with the regulation of international air navigation and in particular