Lance Cpl. Kerry Heinen, an air traffic control communications technician with Marine Air Traffic Control Mobile Team, Marine Medium Tiltrotor Squadron 262, 31st Marine Expeditionary Unit, function checks a PRC-117 radio during a communication equipment maintenance and synchronization exercise (COMEX) aboard the USS Green Bay (LPD 20), Pacific Ocean, Feb. 4, 2017. The COMEX allowed communications specialists and technicians from the air, ground and logistics elements of the 31st MEU to synchronize and repair equipment while establishing communications between the Marine Air-Ground Task Force Elements. The air-ground task force concept is designed to thoroughly exploit the combat power inherent in air and ground assets by closely integrating them into a single force under one commander. The MEU brings what it needs to sustain itself from the sea for the rapid accomplishment of the mission or to pave the way for follow-on forces. (U.S. Marine Corps photo by Sgt. Tiffany Edwards/Released)