The JR-042 is a 10x42mm roof prism binocular. These binoculars feature BAK-4 prisms and fully multi-coated optics for crisp, clear viewing. Large 42mm objective lenses gather plenty of light to ensure the viewing image is bright even in low light conditions. The JR-042, 10x42mm binoculars are O-ring sealed and nitrogen purged making them waterproof and fogproof. Large focus wheel turns smoothly for precise focus adjustments.