The Celestron Sky Master DX 9x 63 binoculars are ideal for astronomical viewing or for terrestrial (land) use, especially over long distances. The Sky Master models feature high quality Ba K-4 prisms & multi-coated optics for enhanced contrast. Celestron has designed & engineered the larger Sky Master 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 magnification & 63mm diameter objective lenses.