Staff Sgt. Nathan Knight, 455th Expeditionary Logistics Readiness Squadron cryogenics supervisor, opens a valve on a 400-gallon liquid oxygen tank, Bagram Airfield, Afghanistan, Sept. 14, 2016. Cryogenics Airmen work with liquid nitrogen and liquid oxygen that is stored into aircraft, providing aircrews with pure oxygen at altitude during missions in support of Operation Freedom’s Sentinel. (U.S. Air Force photo by Senior Airman Justyn M. Freeman)
<br>Unit: 455th Air Expeditionary Wing
Senior Airman Justyn Freeman
Taken on 14 September 2016
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