I think the shower curtain rings really smart. To my mind, they can also open and close well. Roll really good. In the reviews of other rings of this type from other vendors I've read, the balls would every now slide down and then tilt the curtain until it pushes the balls back up. These rings can this really should not happen as a thickener in the wire at both ends of the row of balls at the balls in my opinion, can not get to slide down. Exceptionally quiet, the rings are not. It sounds just as if metal balls roll on metal; and so it is indeed. How concerning is. Rust development verhällt, I can not yet assess.