OttLite replacement bulbs and tubes deliver the right mix of brightness and contrast to bring true colors and comfortable clarity to your world. You’ll see colors accurately and fine print and details with ease under this unique low heat, low glare illumination that helps reduce eyestrain. Warranty is void if used in lamps other than OttLite 18 watt lamps. Details: Natural Lighting 8.75'' x 1.75'' 18W (B) High-definition Bright, energy efficient Rated to last 10,000 hours Fits lamps L18514, T8637T, OLF018TC and OLFX18TC