Chemical, biological, radiological and nuclear defense specialists with Combat Logistics Regiment 27, 2nd Marine Logistics burn 2-chlorobenzalmalonoitrile, or CS gas, during a mask confidence exercise aboard Camp Lejeune, N.C., Oct. 31, 2013. CS, also called tear gas, creates a burning sensation on skin, eyes or in lungs and allows the service members to build confidence in their ability to properly wear of M50 Joint Service General Purpose Masks and Mission Oriented Protective Posture clothing.