Only a genuine verilux bulb fits in the socket of a verilux lamp. This patented 27 watts bulb is uniquely designed for verilux lamps but can also fit several other brands of lamps designed to deliver 150 watts of full spectrum lighting. Lasting up to 10,000 hours, this bulb contains a special blend of earth phosphors to produce a pure, naturally soothing light that improves contrast, color brilliance and visual focus. This verilux natural spectrum bulb makes reading and other tasks more efficient and enjoyable.