LED tubes are made that are pin-compatible with, and designed to replace, standard fluorescent tubes. Most LED tubes available can be used in place of T8, T10, or T12 tube designations, in lengths of 2, 4, and 8 feet. Some LED tubes are designed to drop directly into an existing fixture, while others require rewiring of the fixture to remove the ballast. An LED tube generally uses many individual LEDs to point light downward toward the subject. This differs from most fluorescent tubes that create light 360 degrees around the center axis of the tube, which the fixture then reflects downward.