In fact, as I discovered after receipt, this "mechanism" consists of the axis around which the branches are articulated, serrated over half its width and smooth on the other. By pressing it, it "sloppy" opening the lock. And a leaf spring returns the piece in place when pressure is released, thereby locking the selected aperture. Simple and likely sustainable.
The opening precisely, and contrary to conventional power strip clamp can be adjusted almost continuously on all available amplitude. The counterpart is that this mechanism introduces a vacuum game a little more important than on a conventional strip. By cons, once the opening set, there is no risk that it "jumps". On this model, the maximum "useful" opening is about 4.5 cm, a total length of the clip of about 25cm.
The construction also proves a little different from that of a conventional clamp strip. Indeed, on this key hinges are entrepassées, which avoids creating a torque when tightening. Finally, the particular shape of the clamp and serrated jaws are used to "hang" more easily on the tube, thereby avoiding the sliding and requires less effort.
In the end, a clamp that looks pretty reliable air and fulfills its role. Only time will tell if it will be as durable as a standard power strip. But for now, I do not regret that choice.