c. 1940's vintage american industrial die cut steel "keep guards in place" factory instructional sign designed and fabricated by the parker metal decorators co., baltimore, md. a large assortment of similar cautionary & notification signs were painstakingly removed from building after building of an old st. louis meat processing complex/factory undergoing demolition. the baked enameled sign contains surface wear consistent with age. the four nail and/or screw holes are for mounting purposes. measures 6 1/2 by 9 1/2 inches.