Apollo Command Module Cabin Precision Leak Calculator Assembly, measuring 19 x 19.25 x 10 and weighing approximately 30 pounds, with North American Aviation parts label to lower right reading: "Precision Leak Calculator, Assy. OF, Part C11-000900, Serial 001, Contr. NAS9-150, Model 11FC-0009, Design Activity, North American Aviation, Inc., Space and Information Systems Div." This uncommon piece of ground support test equipment was used to confirm pressure integrity of the Apollo Command Module prior to launch; it bears maintenance, calibration (dated January 1980), and Rockwell/NASA property stickers. The upper portion features two large meters for "Test Gauge" and "Inches of Water," with the lower section composed of "Supply" and "System Test" valves and five rotating knobs related to "System Shutoff," "Bypass," "Supply Shutoff," "Vent," and "On / Off." Back is stamped as "Assy C11 000900-21, S/N 001."