Bright, multicoated lenses and BaK4 high index prisms: Deliver bright, high-resolution images. Smooth central focus knob: Fast range of focus for quick viewing. No bird goes unseen. Ergonomic body design: Comfortable for extended viewing. Waterproof/fogproof: Nitrogen filled and O-ring sealed. Long eye relief: For a clear and comfortable view, especially for people who wear eyeglasses. Unique click-stop, twist-out eyecup design: Delivers both long eye relief and variable eye relief to customize these binoculars to your eyes and accommodate glasses. Durable and protective, rubber-armored coating: Provides a sure, non-slip grip, wet or dry. Manufactured responsibly with lead and arsenic-free Eco-Glass