Capitalizing on the fact that water is non-compressible, this wrench instantly adjusts to any size nut or bolt that fits in its little — I don’t know the technical term, so I’m just going to call it its wrench-hole. Uh oh, here comes the science!
Essentially the adjustable part of the wrench is restricted in its movement by a fluid inside the handle, which has nowhere to go once you twist the little stopper. Ingenious, but I actually like having lots of wrenches around. Makes me feel like a real man. Even though the high-tech view there makes it look like a sex toy from Tron 2.
Get one from ThinkGeek for the tool-lover in your life.