Apollo Command Module Block I fuel quantity indicator manufactured by Simmonds Precision Products, measuring 4.75 x 6 x 5.75, labeled on the reverse, “Display Gage, N.A.A. Control No. ME 181-0049, Contract No. NAS 9-150, Serial No. 08275PDG6040.” Reverse also bears a date of October 29, 1965. Used to measure fuel and oxidizer quantities of the Service Propulsion System (SPS), the front of the unit has four toggle switches, a circular gauge, and two analog counters to provide readouts of propellant quantities used during spacecraft maneuvers; external casing is not present. In very good to fine condition. The primary Quantity Sensing System consisted of 13-foot long cylindrical capacitance probes located in the fuel tanks, which registered changes in fuel level during thrusting to be signaled on the Command Module displays. A rare piece of Command Module hardware that was used for a mission-critical task.
