Marines with Kilo Battery, 1st Battalion, 10th Marine Regiment, 2nd Marine Division put on gasmasks to train for contaminated environments during exercise Rolling Thunder aboard Fort Bragg, N.C., Oct. 19, 2014. After properly securing their masks, the Marines tested their equipment to ensure it had an air-tight seal and practiced procedures to properly clear any contamination that managed to get into their masks. (Marine Corps photo by: Cpl. Jorden M. Wells/released)