This 4.5 by 3 by 1.5 inch indicator meter (above, right) was removed from a Command Module ground trainer used by the astronauts at NASA's Manned Spacecraft Center (now Johnson Space Center) in Houston, Texas. Used to gauge signal strength, a red ID label on its side reads in part, For Use On Ground Instrument Trainer Only, Part No. 690707, Serial No. 11, Link Div. General Precision Inc. The history of the switches (above, left) is unknown; they are typical of the switch used in both the Command and Lunar Modules.