Staff Sgt. Gordon Williamson, 28th Civil Engineer Squadron heavy equipment technician, motions for Christy Wolfe, 28th CES material controls supply technician, to set down parts on a truck at the Material Controls warehouse on Ellsworth Air Force Base, S.D., May 8, 2013. Material Controls Airmen are responsible for managing more than 100 types of parts and equipment that provide the 28th CES Airmen with supplies they need to complete their mission. (U.S. Air Force photo by Senior Airman Kate Maurer/Released)