Aircraft-grade aluminum, single-piece construction with anodized finish for extreme durability; Laser-etched adjustment indicators and push-button illumination controls for tracking east; Nitrogen gas purging prevents internal fogging over the operating temperature range; The rugged design prevents damage from heavy recoil and rough handling; The single-piece tube and o-ring seals prevents moisture and dust from entering the scope even in the harshest environments; XC high-density, low dispersion glass with anti reflective coated lenses provides efficient light transmission and unmatched edge-to-edge clarity