You were born with two eyes, so why not use both of 'em when stargazing with a telescope? Now you can, and you will be pleasantly surprised at what a difference it makes. The effect is most pronounced on the planets and Moon, but even deep-sky objects seem to have more clarity and depth. And now this popular accessory comes with a thread-on 2x Barlow lens, so you can choose two levels of magnification. The hinged aluminum housing contains fully multi-coated BAK-4 prisms that provide high light transmission. You can use almost any matching pair of 1.25" eyepieces. Individual helical focusing collars ensure a sharp focus for each eye. The viewer's 1.25" nosepiece is threaded to accept filters. The Binocular Viewer works with all types of telescopes. On reflectors or short-focal-length refractors you may need to use the barlow lens to accommodate the requirement for 4" of additional inward focus travel.