There are no knobs or dials to control the cables but they do move manually. The bottom vent has knobs to open and close manually for heat under the dash. The main tube on the back of the assembly measures 2-7/8 in overall diameter.Do not miss out on this hard to find part to set your car or truck apart from others at the car shows and cruises. Please do your own research to make sure the parts will work for your application. Please review all of the pictures for a detailed view of the condition of the parts. Please let me know if you have any questions regarding the types of payments that are acceptable.