U.S. Air Force Staff Sgt. Patrick Bentley, 20th Civil

U.S. Air Force Staff Sgt. Patrick Bentley, 20th Civil Engineer Squadron firefighter, trains with compressed air foam at Shaw Air Force Base, S.C., March 10, 2014. The new CAF system is a way of cooling down a structure that is on fire by producing millions of bubbles that trap British thermal units, the amount of heat required to raise the temperature of one pound of water. (U.S. Air Force photo by Airman 1st Class Jensen Stidham/Released)