The Starlight Instruments SCT MicroFocuser provides the smoothest control for fine focusing. Two speed focus knobs allows for standard or 1/10th-speed focusing, making it extremely accurate. Excellent smooth focusing for imaging and visual observing. The focuser is precision-machined and anodized black with a brass fine-focus knob.
The SCT MicroFocuser is easily installed in place of the original focus knob on most Celestron 11" SCTs.
I used it on my Celestron Nexstar 11” GPS I sold. New $189, I'll sell my used one for $140 shipped, insurance extra.