Bulbs with a GU24 base differ from the standard screw in bulbs in that they have two pins at the bottom that twist and lock into a GU24 fixture. These bulbs are conveniently self ballasted, meaning the ballast is attached to the bulb and can be replaced easily. Like other compact fluorescent bulbs, GU24 base bulbs are available in many wattages, sizes, and colors in addition to having received the Energy Star stamp of approval.
Learn more about GU24 Base Bulbs.