Aerial Refueling Telescoping Boom Indicator, KC-97L Boeing Stratotanker 1952 USAF
This offer is for a vintage Cold-War-era aerial fueling Telescoping Boom Position Indicator, made by Liquidometer PN EA-308-1, as used in the US Air Force's KC-97L Stratotanker (and likely earlier versions given its date stamp of 1952), as depicted in its Flight Manual (unfortunately the page showing the indicator does not photograph well). This indicator appeared on the boom operator's control panel and indicated the length of the refueling boom as it is extended from the rear of the aircraft to mate with the aircraft being refueled. Measures 3.25in diameter and ~3in deep.
It is in excellent condition given its age. The dial markings are clear and the glass and case are intact. See photos. It has a date stamp of January 14, 1952.