I don't like other mechanics or people who end up pulling wheel bolts so often, now with this size 21.5 it fits perfectly and takes all those stubborn hard to fit nuts.
This tool works great on swollen GM nuts. We used to constantly swap them out because they got stuck in the outlet. This outlet allows us to reuse the jam nuts, saving us money.
When the union nuts swell it can be difficult to put the head on to remove them, it fits almost perfectly unlike 23mm which only makes the problem worse. I'll get a second one in each of our cars in case we need one when I'm not home.
In the Midwest, the roads are salted in winter. Ring nuts on cars are soaked in salt and regular sockets sometimes don't fit. Well, many of my clients are on a tight budget and refuse to buy new nuts. This socket really works in such cases.