Orion 8733 20mm Sirius Plossl Telescope Eyepiece This 20mm focal length 1.25" eyepiece is ideal for all types of telescopes: reflector, refractor, and catadioptrics such as Maksutov-Cassegrains 20mm telescope eyepiece excels at low power scanning of open star clusters and viewing of nebulas and larger galaxies Offers a 52 apparent field of view for clear, sharp images of impressively high contrast Multi-coated for excellent light transmission and bright, clear views Plossl eyepiece design features 4 lens elements for clear, crisp views and high light throughput