Master Sgt. Robert R. Snyder Jr., Air Forces Central Force Protection liaison officer, wears an elevation training mask, in an effort to improve his cardio and ability to endure higher terrain. Snyder is deployed from Scott Air Force Base, Ill. (U.S. Air Force photo by Technical Sgt. Raymond Hoy)

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Photo by: Technical Sgt. Raymond Hoy |  VIRIN: 130417-F-FU332-001.JPG