The ones I have aren't very safe. I've had a few instances where they'd start sliding down the bar. One time the weights actually fell off and the barbell tipped over and went through the wall next to my bench. I need ones that securely clip on because these screw ones don't hold very well. I need 4 small ones for my dumbells, and 2 larger ones for the barbell. They both have a diameter of roughly 1 1/4". Any websites that sell these?