Rare Block Mother Civil Defense Sign Cold War Military

Near mint never used sign. A few scratches but excellent, heavy metal, embossed letters, approx 8 1/2" by 16". A real find in this condition. Only a very few "Block Mother" signs were made. I understand they were used on select sites w children could gather with a "Mother" in case of an attack, a part of rare history. I've never seen another one. Buyer pays shipping.