U.S. Air Force Airman Steven Benton, Kevin Oseguera, Airman 1st Class Kevin Reese and Airman Adam Allen, 366th Training Squadron, Explosive Ordnance Disposal course is performing closed/open/closed to check the continuity of their firing systems in preparation to set off C-4 explosives on Aug. 26, 2013, at Sheppard Air Force Base, Texas. (U.S. Air Force photo by Frank Carter/Released)