single c. 1950's vintage american industrial "do not operate" danger sign designed and fabricated by the stonehouse steel sign company, denver, co. the reinforced sign contains a nicely aged surface patina from prolonged exposure to a factory work environment, as well as handwriting and a white paint splatter. it reads "danger / do not operate / man working / on repairs". the sign contains two holes at the top corners for mounting and a wire hanger. the danger sign was salvaged from the non-extant a. finkl & sons foundry complex, chicago, ills.