SPANGDAHLEM AIR BASE, Germany – Tech. Sgt. Jeffrey Cunningham, 52nd Civil Engineer Squadron, uses the buddy system to practice drinking through his chemical-biological mask using a canteen during a chemical, biological, radiological and nuclear class Sept. 9. Airmen learn how to drink water with their masks on to stay hydrated should they have to wear mission oriented protective posture 4 for a long period of time. (U.S. Air Force photo/Airman 1st Class Staci Miller)