Orion 8739 6.3mm Sirius Plossl Telescope Eyepiece This 6.3mm Orion Sirius Plossl eyepiece is ideal for all types of telescopes: reflector, refractor, and catadioptric Superb 6.3mm focal length 1.25" eyepiece for high-power planetary and lunar observation in any telescope Offers a 52 apparent field of view for clear, sharp views of impressively high contrast Fully coated optics with magnesium fluoride on every air-to-glass surface to reduce reflection and increase light transmission Eyepiece barrel threaded for use with 1.25" Orion filters