Soldiers from Headquarters and Headquarters Company, 301st Maneuver Enhancement Brigade, prepare to enter a mask confidence chamber as preparation for a response to a Chemical, Biological, Radiological or Nuclear (CBRN) attack, at Joint Base Lewis-McChord, Washington, January 21st, 2017. The purpose of the training was to familiarize soldiers with the M50 Joint Service General Purpose Mask, and to ensure that they are prepared to respond to a CBRN incident or attack.