Bushnell H20 8 x 42 Roof Prism Binocular Roof prism binoculars with 8x magnification and 42-millimeter objective lenses BaK-4 prisms and multi-coated optics offer crisp clear images with improved light transmission 100 percent water and fog proof construction: O-ring sealed and nitrogen purged Non-slip rubber armor absorbs shock and offers a firm grip; twist-up eyecups Large center focus knob; long eye relief; limited lifetime warranty