Focusing a telescope by hand can cause the image to shake or even move completely out of the field of view, especially at high magnifications. But with the AccuFocus electronic focuser, those annoyances are a thing of the past. Using the pushbutton hand controller you get smooth, precise focusing, without vibration. Choose any speed from coarse to very fine. The DC motor installs easily and works with many telescopes. It's powered by one 9-volt battery (included) in the hand controller. Bracket, hardware, and coil cable are also included.