What a unique sign!!! It looks to be hand painted on wood. The size is 7 3/4"X8". Here is the history....the sign came out of an old hydro-electric power plant (circa 1910) on the Missouri River in Great falls, MT. It was a warning sign for copper low hanging knife switches on the "high tension" floor of the plant. There are two of these signs. One is in the hands of a good friend and collector. I'm pretty sure that his will never be offered up for sale. My price for this most unusual and extremely rare sign is $125.00.