A handy person from San Diego says:
January 28, 2016
Hello, I would like to replace the rollers on my patio door. The model is sgd-r20-96x82. Please let me know which rollers to order.
Paul from SWISCO responded:
January 29, 2016
That code might suggest you have the old Capitol patio door, but I can't be totally positive. Start by looking at either our 81-078 or 81-086 and seeing if either compare to your existing part. If neither match, remove it from the door and show us a few pictures of it. We can try our best to find a good match.