Apollo Block II Service Propulsion System (SPS) Propellant Quantity and Utilization display gauge, serial No. 08275PDG8010, measures 4.75 x 6 x 5.75, and is stamped on the reverse, “Display Gage, N. R. Control No. ME 181-0139-011.” Reverse also bears a Simmons Precision Products Inc. stamp, as well as 1968 and 1971 stamp dates. Gauge has a display for remaining oxidizer and fuel, a test switch, a dial to indicate an unbalanced mixture, and three switches along the bottom that control the oxidizer flow, as well as the mode of the PUG. Located on Panel B of the Command Module main control panel, this gauge would measure the remaining fuel and oxidizer quantities and display and control the fuel/oxidizer mixture ratio. In fine condition. RR Auction COA.