Pictured here are the beautiful Pyrex 701 glass insulators (CD 331) "on duty" in the Pacific Northwest. These lovely power pieces are a light straw color, and look like huge diamonds sparkling in the sunlight. To an avid insulator buff, this is one of the prettiest sights in the world!

The Pyrex 701 weighs approximately 38-1/4 pounds, and is the largest one-piece glass insulator ever made. It stands nearly 11 inches tall and measures 15 inches across. These gorgeous gems were made to withstand up to 70,000 volts, and date from about 1923 to about 1941. The Pyrex glass of which they are made has a special heat-resistant quality.

The embossing, located on the outside of the top skirt, reads, "Corning Pyrex T. M. Reg. U.S. Pat. Off. Made in U.S.A.". The embossing crosses over the mold line on some units.

There are very few places in the United States where these giant jewels can still be seen in service. Some of these areas are remote and not accessible by automobile. But just to see these beauties in action is a thrill beyond description.

The Pyrex 701 is truly the grand-daddy of all one-piece glass insulators, and is a real treasure in any insulator collection.

Below is a sketch showing the size of the Pyrex 701 in relation to that of a Hemingray 42.