Advanced Apochromat Optical System with ED (Extra-low dispersion) glass minimizes color fringing to the furthest limit of the visible range; Field Flattener Lens System delivers sharp images all the way to the periphery; Multilayer Coated Lenses and Prisms for natural color fidelity; Optimised Focusing System for fast focusing; Aluminum alloy body for high durability and comfortable observation; Built-in Sliding Sunshade; Total Reflection Prism for an Incredibly Bright, Clear View; Type 1 Bayonet Mount with locking system makes eyepiece attachment/detachment easy and secure; Waterproof performance for inclement weather; Nitrogen-filled and O-ring sealed