Celestron"s SkyMaster Series of large aperture binoculars are a phenomenal value for high performance binoculars. Ideal for astronomical viewing or for terrestrial (land) use, especially over long distances. SkyMaster models feature high-quality BAK-4 prisms and multi-coated optics for enhanced contrast. Celestron has designed and engineered the larger SkyMaster models to meet the special demands of extended astronomical or terrestrial viewing sessions.