170807-N-SL853-091 GREAT LAKES, Ill. (Aug. 7, 2017) Recruits practice donning their gas masks and establishing a seal in preparation for the confidence chamber at Recruit Training Command (RTC) in Great Lakes, Ill. The confidence chamber is part of Fire Fighting II class where recruits build confidence in their equipment and its reliability during potential biological or radiological attacks. Approximately 30,000-40,000 recruits graduate annually from RTC. (U.S. Navy photo by Ensign Seth Schaeffer/Released)