This opener is a small marvel. I would learn insane how it works (so far as I can only speculate). In the first experiment, I thought, it's broken. One sees in turning absolutely nothing (the can turns, but the lid stays where it is). Also you can feel no resistance, no snapping. The opener is just on the can lid. But if you then the round has finished, it tweaks with the attached clamps slightly the edge, and even the cover is removed. As I said, great thing, but the technique is beyond me ....