The Orion Accufocus is an electronic focuser. This electronic focuser suits quite well to being used on the William Optics Megrez 80 SD refractor with it's single speed focuser. I am not sure how this would go on a dualspeed focuser. An idea would be to use a drive belt instead of direct attachment.
Using tis Orion Accufocus on my William Optics Megrez 80 refractor I have always been able to achieve accurate focus with small adjustments being permitted by the slow mode of the focuser. This helps enormously with astrphotography as focus adjustments are much easier repeatable with higher accuracy than with manual focusing (I find anyhow).
If you are looking for a motorised focuser for your William Optics telescoe this Orion Accufocus is a good place to start. Moving up from it in terms of quality and functionality I would recommend a RoboFocus unit. RoboFocus units can be adapted to any telescope by way of using supplied brackets an drive belts. They are high precision and able to be integrated with automation via thir PC link. | 
