CFL 4-pin replacement light bulbs are an energy efficient alternative to traditional incandescent. These bulbs last up to 10 times longer and use 75 percent less energy than an equivalent incandescent light bulb with the same light output. These 4-pin replacement CFLs are for general illumination applications with fixtures that have electronic and dimming ballasts-everything from recessed or down lights to wall sconces and outdoor lights. These light bulbs contain mercury. Dispose of according to local, state or federal laws.