LED UL Type A linear lamps are plug-and-play to install into an existing fluorescent light fixture and operate from its ballast, so there's no need to rewire, add drivers, or modify electrical components. They allow a simple transition when upgrading from fluorescent lamps to more energy-efficient, longer-lasting LEDs. For proper operation, installers must verify that these light bulbs are compatible with fixture ballasts. Each box contains 20 bulbs.