Pentax ZD 10x50 ED Binoculars Premium multi-layer coatings assure the maximum light transmission through the binocular. The result is bright, crisp, true-to-life images in the widest range of viewing conditions. Specialized protective coating repels dust, water and grease to keep your optics clean and your image quality at its peak. Magnesium alloy construction balances durability and weight. The lightweight design is built to handle rough and tumble conditions of lifes adventures. Aspherical lens elements provide exceptional edge-to-edge sharpness. To assure that items on the edge of your field of view are just as sharp as those in the center. Phase coated roof prisms allow the max light transmission for sharp, high contrast images. Waterproof and nitrogen-filled (JIS Class 6) to handle the most extreme weather conditions (submersible to 1m).