20-watt replacement bulb (type M) for specific OttLite lamps * OttLite 508 technology means accurate colors and details--with no harsh glare or distortion * Energy-efficient bulb lasts up to 10,000 hours * Offers about the same light a 75-watt incandescent bulb * Measures 2-1/8 inches in diameter by 5-1/4 inches high