BSA Created the Catseye to help hunters see game better in low light. They made it bright with an extra large objective lens to gather more light. Camera quality glass ground to exact specs. for a clear, undistorted, image. The objective & ocular lenses were Fully multi-coated for more brightness as a special feature. They also made the ocular lens have a larger diameter than most scopes. This combination creates a 4" to 5" eye relief. One-piece aluminum tubing covered with Shadow Black coating, a sprayed on, baked rubber coating that gives a reflection-free, soft black finish.