HD Optical System Optimized with select glass elements to deliver exceptional resolution, cut chromatic aberration and provide outstanding color fidelity, edge-to-edge sharpness and light transmission. Fully Multi-Coated Increase light transmission with multiple anti-reflective coatings on all air-to-glass surfaces. Dielectric Coating Multi-layer prism coatings provide bright, clear, color-accurate images. ArmorTek ® Ultra-hard, scratch-resistant coating protects exterior lenses from scratches, oil and dirt. Phase Correction Coating on roof prism models enhances resolution and contrast.