 High-end safe rooms may have a gun closet, a biodefense air-filtration system that removes biological and nuclear contaminants, and a panic button that locks down the entire house.Safe rooms can be hidden behind many household features, such as mirrors, wardrobes, bookcases, sliding bookcases, and even fireplaces.Warships with CBRN protection generally have a central citadel, with a degree of armour protection as well as a filtered air system.