The TZ-821 Tracker from Carson Optical is a full featured Binocular with fully-coated ruby lenses that reduce internal glare, reflection, and produce crisp, bright images. Special coatings provide unsurpassed infrared and ultra-violet protection, reducing eyestrain and improve image contrast. The Tracker Binocular has a center focus knob with an independent right diopter to adjust maximum focusing flexibility for all types of vision. These Binoculars feature roll-down eyecups for eyeglass wearers.