TEAR GAS CHAMBER U.S. Marine Corps Sgt. Carl Miller drinks from a canteen attached to his XM50 joint-service general-purpose mask in a tear-gas filled chamber on Camp Pendleton, Calif., March 10, 2011. Miller, assigned to the 11th Marine Expeditionary Unit, and about 100 unit members, drilled with the masks as part of chemical-biological-radiological-nuclear defense training. SHARE IMAGE: Download Image: Full Size (0.07 MB) Photo By: VIRIN: 592006-K-SFW28-251.jpg Photo Gallery