ED lens: minimizes chromatic aberration, accurate color reproduction, improved resolution and contrast. Easily transportable in the vest or coat pocket, in the belt bag, or shoulder bag. Magnification range of 9-27 x ranging from binoculars and telescopes. Minimum development of 3 meters perfectly adapted to the ornithological requirements. Waterproof and filled with nitrogen, the telescope is protected from bad weather, wet conditions and other environmental problems