DAVIS-MONTHAN AIR FORCE BASE, Ariz. -- Senior Airman Brian Macmillan (left) and Marine Lance Cpl. Chris Squires perform quality testing on a refueling unit. Airman Macmillan is a fuels analysis laboratory technician with the 355th Logistics Readiness Squadron, and Corporal Squires is a reservist performing two weeks of training here. (U.S. Air Force photo by Airman 1st Class Christina D. Ponte)