The OttLite Telescoping Lamp was designed to provide amazing flexibility unlike any other lamp available today. The 360 degree rotation at the base and the flexible shade joint allows the user to position the light exactly where it's needed, and the height adjusts from 10 1/2 in. to 20 1/2 in. Combine all this innovation and functionality with superior lighting. High Definition Lighting Technology improves image and detail resolution with a balance of wavelengths that enhance vision and peak at the optimal level for comfort of the human eye. Includes long-lasting, energy-efficient 15-Watt High Definition Natural Lighting bulb, rated to last up to 8,000 hours. OttLite 508 Illumination technology. Base diameter: 5.0 in., Height: low 10.5 in. to high 20.5 in.