5 DIOPTER Desk Clamp Provides undistorted magnification wide viewing area and a glare free fluorescent light 3-diopter (1.75 magnification-focal length: 13 ) 5-diopter (2.25 magnification-focal length: 8 ) Fully adjustable precision constructed and spring balanced to maintain any desired position Includes 3 prong plug grounded cord set with molded plug and 22 watt circuline fluorescent tube Magnifying lens 5 diameter