Our Daylight Universal T8/T12 LED tubes replace 48-inch T8u1-inch diameteruand T12u1.5 inch diameterufluorescent bulbs using the existing fixture and electronic ballast. It's slim size fits in the same fixtures as traditional 48-inch T8 and T12 fluorescent bulbs. Why make the switch to LED? Our LED tubes provide long 16-year life based on six hours use per day, so you'll replace less often. They use less energy than a 32-Watt T8 or 40-Watt T12 fluorescent tube with nearly the same light output helping you save money on energy. And, they're mercury free. Use Daylight Universal LED tubes in active spaces and commercial applications like light industrial and clean rooms to provide very cool, bluish-white light.?