Senior Airman Nicholas Macdonald performs a night vision goggle inspection Aug. 8, 2013, at the 437th Maintenance Group Precision Measurement Equipment Laboratory at Joint Base Charleston, S.C. The Airmen from Shaw Air Force Base, S.C. conducted the training here because their night vision inspection equipment was undergoing maintenance. The Airmen confirmed that the optics in the night vision equipment work properly. Macdonald is a 20th Component Maintenance Squadron PMEL calibration technician from Shaw AFB, S.C. (U.S. Air Force photo/Senior Airman Dennis Sloan)