This is the Lumo Pro “Superclamp”, or the actual name, the LP653 Studio Clamp. It is fairly large and the jaws open up by spinning the handle, which allows it to be clamped to door jambs, around pipes, basically anything that you can fit the jaws around.

Handy to have, if you don’t have a light stand or need to stick a light in an area that you can’t fit a stand.