Lance Cpl. Christopher Barnes, chemical, biological, radiological and nuclear defense specialist, Marine Aircraft Group 13, burns tablets of Chlorobenzylidene malononitrile gas during annual training in the confidence chamber at Range 105, Aug. 27, 2015. Marines are required to qualify in the confidence chamber annually. (Official Marine Corps photo by Pfc. Levi Schultz/Released) - Lance Cpl. Christopher Barnes, chemical, biological, radiological and nuclear defense specialist, Marine Aircraft Group 13, burns tablets of Chlorobenzylidene malononitrile gas during annual training in the confidence chamber at Range 105, Aug. 27, 2015. Marines are required to qualify in the confidence chamber annually. (Official Marine Corps photo by Pfc. Levi Schultz/Released)