Grappling Hook Pistol: How specific is it?

Does Grappling-Hook Pistol specifically means it's a pistol or other gun that shoots out a grapple? Or can it be grappling arm, grappling yo-yo, grappling tongue or so on? Because I've seen Grappling-Hook Pistol used as "Grappling Mechanic".

It's really any device designed to fire a tether, though the focus is on the advantage of a compact hand-held device. Items that are improvised is not what the concept is about.