Phase corrected prisms offer a crisp, clear and bright high resolution image.Extra-low Dispersion (ED) glass eliminates chromatic aberration & offers an impressively sharp view as close as 1.6m Key Features: ED (Extra-Low Dispersion) glass for maximum clarifty Dielectric Prism Coating BAK4 Prism Fully Multi-Coated Lenses Lightweight Magnesium Alloy Body Quick Ratio Focus Wheel Twist-up Eyecups with Position Stops Additional Features: Fully Waterproof and Nitrogen Purged (tested 1.5m for 3mins) Stay-on Lens Covers Water Repellent Objective Lens Coating Leather Carry Case & Padded Neck Strap