OttLite H34J3K 508 Illumination 25-Watt Self-Ballasted Swirl Bulb 25-watt bulb provides high-contrast, low-heat, low-glare illumination OttLite 508 technology for colors and clarity similar to natural daylight Designed for exceptional viewing and reduced eye fatigue; self-ballasted Energy efficient and cost effective; lasts up to 10,000 hours Measures 2-1/4 inches in diameter by just over 6 inches high