The CD 133 is a classic insulator style that can vary quite a bit in shape from one mold to another. This one has a narrow, squared-off dome. It was manufactured by Hemingray, and has the H.G. Co. embossing in front. On the rear skirt, there is an embossing error; a backwards 'S' in the word 'STANDARD'. Happy collecting, Sandia www.insulatorstore.com