U.S. Air Force Tech. Sgt. Jonathon Harris, 1st Maintenance Squadron quality assurance manager, secures a bell jar onto the absolute pressure calibration system at Joint Base Langley-Eustis, Va., Nov. 3, 2016. The system provides a standardize pressure to calibrate equipment to, such as tires or medical supplies. (U.S. Air Force photo by Airman 1st Class Kaylee Dubois)