The Kowa TSN-773 77mm PROMINAR XD Spotting Scope with Angled Viewing is a scope of world-class caliber that redefines the standards of color brilliance, detail sharpness, and edge-to-edge brightness. Logically tailored to the most demanding outdoor enthusiast, every technical and ergonomic detail that went into the development of the TSN-770 and 880 series spotting scopes has been examined, perfected, or completely reinvented. This version uses an element of XD (extra-low dispersion) glass in its construction, which greatly minimizes chromatic aberration. This greatly enhances the clarity for crystal-clear images and high color accuracy. Use of Kowa's patented C3 multi-coated optics has made it possible to increase image brightness significantly over prior-generation models. The advanced lens system of these scopes achieves minimal to zero chromatic aberration even at higher magnifications, with consistent high image brightness. The housing is made of magnesium alloy that is designed for maximum durability and lightweight body construction. The result is a compact, ergonomic, and functional design for the die-hard enthusiast who wants only the very best.