Operations Specialist 2nd Class Billy Berrios, assigned to the guided-missile destroyer USS Lassen (DDG 82), tests the effectiveness of his chemical, biological and radiological protective mask at Commander, Fleet Activities Yokosuka. The mask utilizes an interchangeable charcoal filter to protect the wearer from respiratory damage in the event of a CBR attack. (U.S. Navy photo by Mass Communication Specialist Seaman Amanda S. Kitchner)