A great tool to have to help get the belt tight right.
I got this but one also came with the SAB RAW kit I just got and so does the servo arm tool for the front 2 servos to get the arms on them right. This makes getting the belt tension right very easy. If you don't have one I think it's a good Item to have to use when needed. Same if available for other heli brands get theirs to use on their belt tension setup.