Sylvania 20668 cf18dd/e/841 18w w/ g24q-2 base, 4100k 4-pin cfl bulb osram sylvania compact fluorescent lamps uses 75% less energy longer life than incandescent produces less heat protect the environment this suitable for use in unshielded fixtures.-pin cf lamp has an internal end-of-life mechanism that shuts down the lamp preventing abnormal end-of-life failure modes. This lamp was designed for use with high frequency ballasts that do not have their own lamp eol sensing circuits.