Globes are 20 inches in diameter, one piece injection blow molded acrylic with UV inhibitors to help prevent yellowing. They have a minimum opening of 5.25 inches and a maximum opening of 13 inches. This is a custom opening and is not returnable. To request a custom opening, please enter the opening desired in the comments section at the bottom of the checkout page, or call 800-665-3594. If no custom opening is indicated, the globe will be sent with the minimum opening indicated in the description.