Explosive ordnance apprentices Airmen 1st Class Dallas Roll, Matthew Leatherman and Nikolas Cox place plastic explosive C4 into shape charge containers prior to explosive ordnance training Feb. 21, 2008 at Eielson Air Force Base, Alaska. The charge containers hold the shape of the C4, which determines the direction of an explosion. (U.S Air Force photo by Staff Sgt. Eric T. Sheler)