Vortex Optics Razor HD Wide Angle Eyepieces Premium (High Density) extra-low dispersion glass delivers the ultimate in resolution and color fidelity, resulting in High Definition images. Vortex proprietary XR anti-reflective coatings, fully multi-coated on all air-to-glass lens surfaces, increase light transmission for maximum brightness. Optics are sealed with o-rings to prevent moisture, dust, and debris from getting inside the spotting scope. Argon gas purging guarantees superior fogproof and waterproof performance. Ultra-hard, scratch-resistant coating protects exterior lenses from scratches, oil and dirt.