Sunlite 05439-su sl20/blb 20w black light spiral cfl light bulb, medium base, black light blue sunlite black light spiral compact fluorescent lamps fit into most standard fixtures and give off a blb light much like a 75 watt incandescent bulb. These energy efficient cfl lamps can last up to 9.1 years with normal household use of 3 hours a day. This energy saving 20 watt 0, medium base bulb offers 0 lumens of light output and has an average rated life of 8,000 hours.