The celestron skymaster dx 9x63 binoculars are ideal for astronomical viewing or for terrestrial land use especially over long distances the 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 these large aperture porro prism binoculars are weatherproof with a shock resistant rubber covering 9x m