The Zhumell SCT Dual Speed Telescope Focuser is a Crayford design that gives you 11:1 dual speed focusing. For focusing quickly and efficiently without missing important images, you need an accessory that gives you the upper hand. This dual speed focuser includes a 1.25-inch format eyepiece adapter so it works with nearly any telescope. Traveling distance of draw-tube: 30mm. Our focuser is a perfect accessory for Meade and Celestron SCT telescopes, and measures 171 x 107 x 100 mm.