Air Force Master Sgt. Cassandra Doub, left, and Staff Sgt. Andrew Perna secure a piece of matting for a ramp expansion at Bagram Airfield in Afghanistan, Aug. 11, 2016. Doub is a first sergeant and Perna is a maintenance and equipment craftsman assigned to the 455th Expeditionary Civil Engineer Squadron. Air Force photo by Senior Airman Justyn M. Freeman