Despite the name, these rings are not meant to be worn on the hand but stuffed into strange places in and around you car and help pound out dents. Auto Body Tool Mart has them on sale for $22.99 — that may sound steep, but try finding something else that will work (then go buy one of these).
Used for auto body sheet metal shaping and dent repair, the hammer allows you to access small spaces and quickly change the hammer head shape as you work the metal. It’s sort of a cross between a dolly and a hammer. Plus, it looks cool and would make an excellent paperweight.
Ring Hammer [autobodytoolmart.com]