U.S. Air Force members activate MK-124 signaling devices during a water survival refresher course taught by 375th Operations Support Squadron Survival, Evasion, Resistance and Escape specialists at Carlyle Lake, Ill. Nov. 3, 2020. A MK-124 is a versatile signaling device that can be used at night, as well as day to show where a downed airman is located. (U.S. Air Force photo by Airman Isaac Olivera.)