Despite the many positive reviews, I cannot fathom how thin the cord must be on these to get 25 feet into a spool that is 7 inches square and less than 5 inches high. I fear that putting the rated 15A though that would ignite the insulation, assuming there is much to ignite.
It says 16AWG, which is a standard extension cord. There are bigger ones, but this isn’t abnormally thin.
I have two of these and they are great. I can’t speak to the internals of the cord, but the actual thickness and diameter is the same as other extension cords I have and it is able to spool onto the reel with plenty of room to spare - I think this would actually work with a much longer cord as well.