The tension on these clamps exceeds the quality of the plastic they are made of. I got these shipped today and have started using them to secure 1 inch thick material. After I clamped my piece, I did something else, then I heard a loud pop and was hit in the back of my head with a piece of the clamp, which broke under tension. About half a minute later another popped up and the same thing happened, and a few seconds later a third worked. I have almost the same clamps that I have used for manyβ¦