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is a 6-element, fully multicoated optical design with extra low dispersion (ED) glass on the most highly curved surfaces to minimize chromatic aberration which hinders sharp planetary viewing.  With a wide 55° apparent field of view and a large 25mm clear aperture, the X-Cel 25.0mm is a comfortable eyepiece to use.  Eye relief is a very respectable 20mm, so even if you wear glasses you'll enjoy the whole view.  And of course, the X-Cel 25.0mm eyepiece is threaded to accept Celestron's collection of 1.25" eyepiece filters. The X-Cel 25.0mm eyepiece is parfocal with others of the X-Cel series, meaning little or no focusing is needed when changing eyepieces within the collection.