I bought a set (i.e. a pair) years ago, but only used them recently when gluing up some smallish panels. Agree with Oliver that they require “management” to set up - I am thinking of using sticks of somewhat thicker timber to keep the 2x2s apart, when inserting the next batch of boards to glue up. Otherwise a bit of cat-herding required.
Also agree with Herb that additional clamps may be required, especially if there is some bowing in one of the boards. I would have preferred parallel-jaw clamps, but those are hellish expensive in this neck of the woods, whereas these clamps (Chinese made) for once were about half the price here compared to the Peachtree price.
But in the final analysis, they do work as described.