These rotary lock dumbbell collar can be used for 1 inch standard weight lifting barbells or dumbbell bars.If there is only one barbell or dumbbell bar,you can lock two for one side,so that neither side will slide down,This will be an essential material for the gym,which can help you solve the broken dumbbell rod nut in time and reduce unnecessary trouble.These rotating locking rings are a simple and quick way to move plates.When lifting weights,they can also keep the weight plates safely and reliably,You can also give them as gifts to your friends and family,especially athletes.Keep their sports equipment well.