The MK5 was a British gas-mask produced during World war 2 and was also used by other Commonwealth countries such as Canada and Australia. The Mask has a barb where a tube is secured using wire which leads to the filter. The filter is normally painted red or orange and contains charcoal and asbestos making the mask unsuitable for wearing because of the danger of inhaling asbestos.

The mask was used in the original 1973 The Crazies, however the filters were detached and fake filters were glued onto the masks so the actors would be in no danger.