This model is designed to fit open roller door drums. For closed drum style some modification is required. You'll need to fab, or find a 'U' shaped metal bracket, cut to fit, and fasten to the closed drum plate. I used a 1 x 3/8" bolt and lock washer to fasten the bracket to an available threaded opening in the drum. Cut the two plastic legs down on the Vevor roller to fit the bracket. The bracket fits between the legs. You may need to cut a space for the cord to fit, depending on the wall mounted bracket. If your door has a smaller diameter main shaft, simply use a piece of pvc to fill the gap. The pics should give a pretty good idea of what needs to be done. (Don't try this if you're not real handy with modifying things to work...)
After modification and installation the Vevor 800 N roller door closer worked perfectly! It is very quiet and smooth. Highly recommended!