The extendable twist-up eyecups of this eyepiece is ideal for eyeglass wearers. It offers comfort in a parfocal eyepiece that requires little or no focusing when changing from low to high power. The threaded barrels accept 1.25" Celestron thread-in filters. Additional user-friendly features include a shock resistant rubber covering that's scratch and dent resistant, a no slip grip designed for secure handling even in moist conditions, and a roll guard with ergonomic contours that prevent eyepiece from rolling off flat surfaces. Includes 28 mm clear aperture surface lens for comfortable viewing. Recommended for ages 13 and up.