What you saw was a pipe wrench.

You can see the obvious black upper jaw there, with the adjusting nut on the upper jaw.
Not so obvious: the black upper jaw has about 5 degrees of flex/play, rotating about the logo sticker more or less. This means that leaning into the tool causes the jaws to come together slightly, and going the other way (ratcheting the tool) causes the jaws to come apart slightly.
This is designed for pipe (and pipe fittings made to work with this wrench). They are generally round and do not have flats. The wrench relies on the object being round, and gouges into it. The material must tolerate that.
This type of wrench is not the right thing for other fasteners that provide a hex or other means to lock onto the fastener. A pipe wrench would gore up the hex or other head, possibly crack it, and in any case reflect very poor workmanship.
The concept doesn't translate very well to hex fasteners. If the jaw opens enough to slide past the hex on the backstroke, it will slide past the hex on the forward stroke too! Also for the tool to work, the jaw needs to "dig in" to the material to stop it from sliding.
JACK links an open-end wrench with a notch in one of the faces, so you only need to slide it off about 2mm to allow the hex to slip by. The problem is, when engaged, it only has about 2mm of purchase on the most critical corner of the hex. That works under ideal conditions and low torques, so it looks good in the advert. But if the hex is even a little beat up it won't seat... and if too much torque is used, the 2mm contact point will round over, and then you'll really be up the creek... you won't be able to use other tools either.