Fallout Shelter T-Shirt Solid colors: 100% Cotton; Heather Grey: 90% Cotton, 10% Polyester; All Other Heathers: 50% Cotton, 50% Polyester Imported Machine wash cold with like colors, dry low heat Cold War era fallout shelter sign tshirt. Fallout shelters were built, as a civil defense measure, to protect occupants from radioactive debris after a nuclear explosion. Fallout Shelter Shirt Lightweight, Classic fit, Double-needle sleeve and bottom hem