Globes are white acrylic and are 12 inch in diameter with a 3.91 inch outside diameter twist lock neck with 3 notches. Globes are one piece injection blow molded, water and shatter resistant with UV inhibitors to help prevent yellowing. These are made to be used with a 4 inch inside diameter twist lock fitter. If your fitter is larger than than 4 inch inside diameter these will not work. Please see diagram.