Explanation from my husband... In general terms it is a hole punch, however, this tool is a multifunctional tool such as punching holes, riveting, to press bearings in place, blacksmithing, et cetera. In order for this tool to function however one would need the plate that is missing (see top photo... if you look at the shorter metal "shaft" located pretty much in the middle of the tool - next to that you can see where a plate would be attached to it, and, where it would be screwed in to hold it in place). The "ball" at the top is actually a weight which would not be used for hitting with a hammer.