Advanced roof prism design housed in a lightweight composite body. O-ring sealed, nitrogen filled for total waterproof and fogproof performance. Fully rubber armored body and sophisticated multicoated lens. Quick and precise central focus wheel brings in sharp images from infinity to an astounding close up distance of only 9 feet! Sufficient eye relief accomodates sunglass wearers comfortably and allows for preferred individual adjustments with fast twist-up eyecups.