This is a bracket to attach a 28byj-48 stepper motor to a Celestron Travelscope 70 (or any other refractor that uses the same focuser). The bracket fixes to the telescope using the existing focus tightening screw, and the knob replaces the existing focus knob so this is a bolt on accessory that does not damage the scope. You will need a 200mm GT2 belt, two short M3 bolts to attach the stepper, and one longer bolt for the knob (I believe it's a #6 fine). I currently have mine attached to an Arduino Nano with two old limit switches for forward/revee butto, but I plan on using this with Otep later. I will post my schematic and code in the future. PS - it's a bit of an odd shape, so you'll need supports for the bracket.