Well-balanced, bright and steady for long hours on the water. BaK-4 porro prisms for bright, clear, crisp viewing. Fully Multi-coated optics for superior light transmission and brightness. 100% waterproof / fogproof. O-ring sealed and nitrogen-purged to keep out moisture. Highly resistant to saltwater corrosion. Non-slip, non-skid rubber armor cushions bumps and shock, prevents sliding and provides a firm grip when wet. Hermetically sealed. Fold-down eyecups.