U.S. Air Force Senior Airman Cory Littlefield, 35th Communications Squadron, radio frequency transmission systems technician, tests the battery amperage of the mass notification system Dec. 4, 2010 at Misawa Air Base, Japan. The tester uses high resistance coils, which heats up when energized. RFTS technicians maintain more than 200 devices at over 128 locations. (U.S. Air Force photo/Tech. Sgt. Phillip Butterfield)