The Astromania series includes 6 different focal lengths - 32mm, 22mm, 17mm, 13mm, 8mm, 5mm and 3.5mm. This covers an incredibly range of magnifications with just a single eyepiece series - all of which provide an excellent image. The 6 eyepieces in the series are practically parfocal, meaning there is no need to re-focus when changing eyepieces. The Astromania eyepieces - from 17mm to 3.5mm in focal length - have both 1.25" and 2" barrels. A 2" barrel sits directly above the 1.25" barrel. This saves having to fiddle about with extra adapters - just use your 2" focuser for all the different focal lengths.