This belt wrench was found at Value Village. It's simple enough that many could make one based on the picture. There is a slightly larger metal plate screwed to the other side. The belt appears to be a used automotive belt. There is just enough space for the belt to slide to different positions, to change the size. A firm grip locks it in place.
It was probably used for removing oil filters. Could also be handy to hold a drive shaft in place, twist threaded plumbing parts or to extract poles from the ground. I tried it on a big pipe.
That's all for this one, since I know nothing more about it.