Vixen's newer refractors have a fine-focus mechanism that is attached to the existing focuser pinion by a thin metal plate. This plate is a weak point in the focuser system, allowing flexure and play that prevents precise focusing.
Starizona's focuser bracket is a handy fix to that problem. It is a precision-machined, much thicker and more stable plate that replaces the stock thin plate. It is easily installed using the existing screws and adds stability to your telescope's focuser.