These globes are 18-inch in diameter, one piece injection blow molded polycarbonate. Each globe is high quality, water, and shatter resistant with UV inhibitors to help prevent yellowing, resulting in an excellent and long lasting globe. They have a 5.25 inch neckless minimum opening but openings can be made large at no additional cost, giving you the custom fit and finish you desire. Custom openings are not returnable. Shop this globe and many others today.