From verso of card: "This subject shows the examination of respirators at one of London's Regional Supply Depots, of which there are now three in existence. . . . Respirators, after being suitably packed for long storage at these Depots, are then to be moved to store centres. Each store centre is expected to house about 30,000 to 40,000 respirators, and its location is to be determined after consultation with local authorities. In the event of an emergency, respirators would be unpacked at the store centres, prepared for use, and issued to the public through distributing depots which would each handle about 4,000 respirators."