HDC anti-reflection fully multi-coatings increase light transmission throughout optical path to improve color rendition, brightness, clarity, and contrast. Dirt and water-repellent AquaDura coating on outer lens surfaces makes them easy to clean, ensuring clear views. Large, knurled center focusing wheel is easy to manipulate even when wearing gloves. Twist-up four-position click-stop rubber eyecups for comfortable use with or without eyewear. Nitrogen-filled and O-ring sealed to be waterproof for 13'(4m), and resistant to internal fogging when moving through extreme temperatures and conditions