SUPERIOR OPTICS, COATINGS, MATERIALS, AND CRAFTSMANSHIP: With large objective lenses, BaK-4 prisms, and fully multi-coated optics utilizing Celestron’s proprietary XLT coatings, the view through SkyMaster Pro is second to none at its price point. RSR "REFLEX SIGHT READY" RAIL: SkyMaster Pro's unique detachable RSR rail allows you to mount an optional red dot finderscope or other reflex sight. Pointing at astronomical or land-based targets with a binocular has never been easier. FULLY MULTI-COATED OPTICS: Every lens surface is coated multiple times with Celestron's unique XLT coatings to improve color and contrast and maximize brightness. You'll enjoy brighter and sharper images, even when lighting conditions are dim. DURABLE, WATERPROOF BODY: A rubber-armored, polycarbonate housing protects your binoculars from damage and stands up to the toughest weather conditions. They're also fully waterproof and nitrogen purged to prevent internal fogging of the lenses. UNBEATABLE WARRANTY & CUSTOMER SUPPORT: Buy with confidence from Celestron, a leading optics brand in California since 1960. Your purchase includes a Celestron Limited Lifetime US Warranty & US-based expert tech support.