It is a Vim Tool, they were notorious for **** marking on their tools. There is a Vim thread on here. I don't think they cover that particular tool. Truth Tools made a similar primitive looking wrench they called a Pump Nut wrench but it didn't have teeth on both jaws. edit...also, now that I looked, The Truth one's jaw had a more simplistic external hinge for the jaw, whereas this Vim is swiveling in a groove.