The Luminos series eyepieces offer a wide 82 deg.field of view in both high power and low power models, allowing you to make the most of your telescope, whether you own a short, fast refractor or a Celestron EdgeHD telescope. The optical set consists of six or seven elements (depending on the model) and is fully multi-coated for crisp, sharp views. All six Luminos eyepieces are parfocal, which means you can switch out eyepieces during observing sessions with little or no additional focusing required. The Luminos eyepiece body is made of polished and anodized aluminum. A rubber grip runs around the equator of the eyepiece, giving you a secure grip and an easy method for raising and lowering the retractable eyecup. Simply twist the rubber grip to adjust the height of the eyecup. The insert barrel is threaded to accept filters..