"Meade Series 4000 #126 2x Short-Focus Barlow Lens #07273 is a compact ""shorty"" type 1.25"" Barlow. Doubles the magnification of your 1.25"" eyepiece while offering excellent image quality. Our most popular Barlow due to its excellent quality, value, and usefulness on nearly every model telescope sold. Features a 26mm lens aperture, 1.25"" barrel, multi-coated optics, and doubles the power of any 1.25"" eyepiece without adding a very long extension between the telescope and the eyepiece. Insert this into the telescope's eyepiece holder first, and then insert your eyepiece into the Barlow. May also be used in a diagonal mirror either between the diagonal and eyepiece for a 2x magnification factor or between the eyepiece holder and diagonal for a magnification of approximately 3x. Compatible with nearly any telescope which uses 1.25"" eyepieces regardless of brand and even those with limited focus range."