At the pinnacle of roof prism binoculars lies Olympus' Magellan line. They're nitrogen-purged and O-ring sealed for total waterproof and fogproof construction. Vast temperature changes as well as moisture will have no effect upon them. Each lens surface is fully multicoated, and the high-index BaK-4 prisms are silver lined for supreme edge-to-edge sharpness. World-class optics, encased in rubberized bodies which are light for their specifications.