Standard Individual eyepiece focus. Bushnell Marine Binoculars 7x50mm Marine binoculars are a premier choice for boaters. Built to withstand marine conditions. They are nitrogen-purged to provide reliable waterproof/fogproof performance - the 13-7500 and 13-7501 models are even hermetically sealed to further assure no moisture creeps in. Impressive light transmission from BaK-4 porro prisms, multi-coated optics and large UV-coated objective lenses brighten images from dusk-todawn. And, all three models not only float, but easy-grip rubber armoring protects and provides a secure hold should things get rough. Features: BaK-4 porro prisms for bright, clear, crisp viewing. Multi-coated optics for superior light transmission and brightness. Rugged, 100% waterproof construction. O-ring sealed and nitrogen-purged to keep out moisture. Highly resistant to salt water corrosion. Textured center focus knob for easy, precise adjustments (on model 13-7502). Non-slip, non-skid rubber armor cushions bumps and shock, prevents sliding, and provides a firm grip when wet.