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 Lenses: Anti-reflective caotins on all air-to-glass surfaces provide increased light transmission for greater clarity and low-light performance; ArmorTek: Ultra-hard, scratch-resistant coating protects exterior lenses from scratches, oil and dirt. Ultra-hard, scratch-resistant coating protects exterior lenses from scratches, oil and dirt; Helical Focus: Snag-free for faster, easier packing and mounting; Rubber Armor: Provides a secure, non-slip grip, and durable external protection; Argon Gas Purged: Gas purged and O-ring sealed for superior fogproof and waterproof performance in the most extreme conditions; Shockproof: Designed to withstand the highest levels of impact; Tripod Adaptable: Allowing use on a tripod or car window mount; Arca-Swiss Compatible: Designed to fit the Arca-Swiss standard. Allows for a direct mount with other Arca-Swiss compatible products