clamps. Pinching things, maybe not some things, who am I to judge? I haven't used it for whistles or anything else it's normally used for, I'm such a rebel. I had an office chair that slowly sank over time. The lifting mechanism was defective. I lifted it to the height I needed, squeezed these two baddies underneath, didn't move. Not once, not a bit. I think it would probably be useful for normal stuff too.