largely intact c. 1930's american industrial single-sided "high voltage" danger sign fabricated by the strong, kennard & nutt co., cleveland, oh. the reinforced "protexal" sign is comprised of heavy gauge 18 gauge rolled iron with 5 coats of vitreous or porcelain enameled finish. the universal red oval signal or symbol with the word "danger" was first introduced in 1911 by j.w. stonehouse. the sign contains minor loss of porcelain enamel, along with discoloration and/or surface rust. measures approximately 14 x 10 inches.