Designed for the nature-enthusiast who wants to pack light without sacrificing image quality, the Pentax 10x36 A-Series AD WP Compact Binoculars deliver bright clear images while weighing in at just 22.5 ounces. The BAK4 roof prisms are phase-corrected to improve image contrast and enhance color rendition. All of the optics are anti-reflection fully multicoated to maximize light transmission to produce the brightest views possible. In order to cut weight, the housing is made of corrosion and impact-resistant fiberglass reinforced polycarbonate polymer. The material is also temperature-resistant allowing for their use in extreme climates while reducing expansion and contraction wide temperature swings can cause which can make the optical components move out of collimation over time. There optical tubes are nitrogen-filled and O-ring sealed so they can are submersible to 3.3', as well as fogproof in all weather conditions.