Bushnell H2O Waterproof/Fogproof Roof Prism Binocular 100% waterproof, O-ring sealed and nitrogen purged for reliable, fog-free performance BaK-4 prisms and multi-coated optics offer crisp clear images with improved light transmission Non-slip rubber armor and Soft Texture Grip absorbs shock and provides a firm grip 10x magnification and 42mm objective diameter; 12-foot close focus distance; 17mm eye relief Large center-focus knob for easy adjustments; Twist-up eyecups; Limited lifetime warranty