Complete Multiple Coating (FMC): multiple lens fully coated with anti-reflective green film for excellent light and brightness transmission while improving contrast and resolution. 8x21 binocular, with a magnification 8x this binocular can bring subject 8 times closer, 21mmobject lens diameter,it allows more light to come through,and it is very clear for the details even if it is at low light condition Rotatable lifting eyepieces: With the rotating design, people wearing glasses can lift the eyepiece cover and keep a certain di between the eyeglasses and the eyepiece, so that the viewing experience is not impaired and it feels more comfortable. If you want to get the best visual effects, you can lower the eyepiece cover. The BAK4 high refractive index prism has bright, clear images and a sharp contrast that gives you all the details of the object. This binocular also can be used for watching large stage play, vocal concert, a football game, etc.