Sofa savers. Anyone used the foldy stuff?

[Bubblebuttress]

Wondering if hey work and how they work… some sort of concertina shape. Comfortable?

We tried them, they're just strips of mdf side by side contained in a material cover. They were reasonably comfortable, but one by one the mdf strips snapped. I should add that neither of us are more than 12 stone, so you would have thought they ought to be able to cope with that.