U.S. Marine PFC Franco M. Estabillo, Jr., administrative clerk, 11TH Marine Expeditionary Unit (MEU) listens to instructions for use of the M50 gas mask during chemical, biological, radioactive and nuclear (CBRN) training aboard Camp Pendleton, CA, April 19, 2013. The MEU undergoes annual CBRN training to keep personnel mission ready and to familiarize Marines and Sailors with special CBRN equipment. (Photo by: Cpl Jonathan R. Waldman, 11TH MEU Combat Camera)