Introducing Vixen's new SSW 3.5 mm Ultra Wide 1/25" Eyepieces that features an exceptional 83° wide field of view. The eyepiece's 7 element design, features high-transmission/low dispersion lanthanum and exotic glass. This combination offers unparalleled contrast and sharpness, outclassing all competing brands. Full multi-coating on all lens surfaces, in combination with special coating on the lens connecting surfaces, delivers high contrast sharp star images across the entire field of view. No edge darkening or vignetting is evident over the viewing surface, even with fast f/4.0 optics. The advanced multi coating on each lens surface offer high light transmission, over 99.5%, throughout the visible rays of light (430nm - 690nm) and produce extremely bright and clear images.Features:Barrel Size: 31.7mmEye Relief: 13mmAnodized aluminum bodyHexagonal barrel with unique anti roll designSleeve design is applicable to both screw and compression ring eyepiece adaptersRetractable eye cup with rubber grip for great viewing and comfortable handling.