From the ManufacturerThis 1.25" 12.5 mm focal length eyepiece is ideal for all types of telescopes: reflector, refractor, and catadioptrics such as Maksutov-Cassegrains (Mak-Cass). Moderate magnification provided by 12.5 mm focal length design performs well on both deep-sky and planetary subjects. Offers a 52-degree apparent field of view for clear, sharp images of impressively high contrast. Fully coated with magnesium fluoride on every air-to-glass surface for optimal light throughput and bright view quality. An excellent middle ground eyepiece for detailed views at moderate power in any telescope