Pentax SP 20x60 WP BinocularsThe Pentax SP 20x60 Waterproof binoculars feature larger objective lenses which are designed for astronomical as well as terrestrial use in any climate. The larger 60mm lenses are fully multi coated with anti reflective properties that also gather more and improve light transmission along the optical path which works well in low light conditions. Nitrogen purged and O ring sealed you get waterproof and fogproof performance. With the porro prism