Acorn polycarbonate globe 23 inches for replacing existing globes that have aged or cracked. It's easier and better to replace the polycarbonate and get the lighting fixture back like new. They've been used for years on streets, apartments and commercial buildings. This is the classic shape and style that you see on all kinds of street lighting mainly municipal town lighting. The 8-inch opening is very standard for many types of old lighting fixtures that used this type of plastic on the post top. These are a polycarbonate plastic, and so that means it's unbreakable, so these are good to use in areas where vandalism could be an issue. The polycarbonate has a rippled appearance, so it breaks up the light that's inside and causes an even distribution of light. The acorn globe looks great when it's on a boulevard but also has applications for some people that have post commercial lights in your yard lighting. These are a larger type of replacement plastic, and for many home lighting applications, this is going to be too big. It's one piece plastic and so you're not can have any problems with the seam or any leaking, it's going to keep all the moisture out through all the seasons. Call us if you have any questions about replacing your existing acorn globes and whether or not this will give you the right fit.