U.S. Air Force Senior Airman Nick Pratt, 20th Civil Engineer Squadron structures craftsman, uses a sledge hammer to drive in a metal stake, Shaw Air Force Base, S.C., Jan. 10, 2014. Pratt, along with several other 20th CES Airmen, had set up a TEMPER tent to be used as a simulated contamination control area for an operational readiness exercise. (U.S. Air Force photo by Airman 1st Class Jensen Stidham/Released)