It is additional purchase of each size of short wrench. Because the one I bought first was easy to use. It was a purchase assuming use in a narrow place, but it was also perfect for places where you would like to tighten bolts without applying too much torque besides that. Because it was so short it was a good feeling without too much power. Besides the normal size wrench, I think that shorts are aligned and there is no loss. Since KTC is the rest, it is a quality of security.