U.S. Air Force Reserve Staff Sgt. Maurice Wakins and Private 1st Class Stanko Bosnjak test water they have just purified using the H9518-1 reverse osmosis water purification unit. This year's Silver Flag Exercise hosted here Feb. 21-28 allowed USAFE Airmen, Air Force Reserve and members of the Croatian Army for the first time to observe how Airmen prepare to deploy to austere locations.