Air Force Chief of Staff Gen. CQ Brown, Jr. (right), presents a challenge coin to Master Sgt. Alfred McDuffie, 459th Air Refueling Squadron NCO in-charge of mobility operations, at Joint Base Andrews, Md., Nov. 17, 2021. During his visit, Brown coined multiple Airmen for their superior performances in their work centers and their contributions to the Air Force mission. (U.S. Air Force photo by Senior Airman Spencer Slocum)