The high-level outdoor performance of the Celestron Trailseeker ED 10X42MM Roof Binoculars makes them an excellent choice for avid birders and outdoor enthusiasts. The high-quality extra-low dispersion (ED) glass delivers razor-sharp images with excellent color correction, especially in low-light conditions such as dusk or dawn. The fully multi-coated optics and BaK-4 prisms maximize light transmission for the brightest, most detailed images possible. The Trailseeker ED is composed of lightweight and durable magnesium alloy. They are waterproof and have a rubber-coated tough and rigid frame to stand up in tough outdoor conditions. They are also filled with dry nitrogen gas to prevent internal fogging of lenses and have durable twist-up eyecups that make eyeglass and non-eyeglass wearers viewing through the lenses comfortable. Viewing birds, butterflies, plants, or other nearby subjects is easy thanks to the Trailseeker ED's close focus of 8.5 feet feature. This 10x42 binocular is also excellent for enjoying great views of distance subjects and includes a wide field of range so that you can easily follow them as they move. This versatile binocular will become a favorite must-have item for all your adventures.