This high quality eyepiece features a 5-element design that offers superior sharpness. All air to glass surfaces have a multi-layer coating (so these are fully multi-coated, even though the barrel imprint may say "multi coated") for maximum light transmission. The long eye relief allows for a comfortable viewing distance. All lens edges are blackened for superior contrast. The insert tube is smooth-sided and is threaded for standard 1.25" astronomy filters. Ultra wide lens eyepieces offer a generous 66- degree apparent field of view, allowing more sky to be viewed at one time. They provide sharp image right across the field. The rubber eyecups are included for viewing comfort and to keep out extraneous light.