These shower curtain rings are great.  I change the liner in my shower curtain often and it was a hassle with the old rings having to deal with the curtain AND the liner while changing.  These rings solve that problem nicely with the added benefit of sliding easily on the shower rod with the little roller bearings that they ride upon.  Wish I'd had these years ago!

allows changing of the liner without disturbing the curtain...slides easily on the shower rod.
haven't found any yet except maybe that they're such odd little ducks...but that's kind of endearing.