Celestron's X-Cel LX 18mm Eyepiece is designed for comfortable near and deep-space astronomical observation. It is built with a 6-element lens configuration, blackened edges, and anti-reflective fully multi-coated optical surfaces to ensure bright and clear high-contrast images with true color transmission across the entire wide 60° field of view. Celestron engineered the X-Cel LX series of eyepieces with a long 16mm eye relief that brings the user's face back from the scope to minimize vibrations caused by contact with the eyepiece. All eyepieces in the series are completely parfocal, making switching eyepieces convenient by not requiring re-focusing. With a 1.25" diameter barrel, it will fit the most common size drawtubes, visual backs, and accessories; and a rubberized collar provides a non-slip grip especially in cold weather and when wearing gloves. The housing is made of a lightweight and durable aluminum alloy with a reflection-limiting matte anodized finish, and a retractable eyecup that extends with a simple twist for comfortable use with or without eyewear.