The Pentax UP 8-16x21 binocular reverse porro Prism is a compact model, which includes a sustainable dual axle, single body design with synchronized IPD adjustment and full multi-coating for better light transmission. Aspherical lens elements give you a full sharpness from corner to corner. Key Features: Fully multi-coated optics Reverse porro prism design Aspherical lens elements BaK4 Prism for a maximum resolution Dual axle with synchronized IPD adjustment Rubber protection Pull-up eyeshades in combination with a comfortable eye-relief Centrally located lockable dioptre