Type A - Plug-n-Play 4 ft Retrofit T8 LED Tubes replace traditional fluorescent bulbs using the existing ballast in your fixture. That means you don't need to replace or rewire the entire unit just to switch to LED! Available in a range of color temperatures, these LEDs do not flicker or have a delay to reach full brightness like you see with outdated fluorescent technology. Type A T8 LED bulbs will work with most fluorescent ballasts, but it is advised to check compatibility first. If you need help in figuring out the best match for your setup, please reach out to our lighting gurus here at GoodBulb.