The Celestron X-Cel LX 18 mm Eyepiece has a brand new sleek, robust design and a twist-up eye guard. These eyepieces are especially designed for comfort and ease of use. They also have a wide 60 deg field of view and 6-element fully multi-coated optics for magnificent wide field performance. X-Cel LX eyepieces are parfocal and require little to no focusing when changing from low to high power. Features - Wide field of view enhances views of the night sky through a single lens - 6-element fully multi-coated optics create sharper images - Extendable twist-up eyepieces are easier and more comfortable, especially for eyeglass wearers - No slip, rubber grip ring for secure handling, even in moist conditions - Parfocal eyepiece require little to no focusing when changing from low to high power Specifications Suitable for: Celestron SCT-Telescope Focal Length (mm): 18 mm (0.71 in) Angular Field of View (deg): 60 deg Eye Relief (mm): 16 mm (0.63 in) Optical Coatings: Fully multi-coated Barrel Size: 1.25 in (32 mm)