I got so tired of my previous shower curtain hooks coming off the curtain rod!  So I got these.  They roll smoothly along the rod, and they STAY ON!!!  Yay!  They're a bit elongated, and LOOK somewhat like pierced earrings in an old woman's ear -- stretching the hole and lobe -- although they're not actually stretching anything, they just look like it.  The reason I gave them 4 stars and not 5 stars is because friends have told me that once they're on the curtain, if you wish to change them to a different curtain, you'll probably end up breaking a few of them (or more), because they become more brittle with every opening.
I have seen some, somewhere, that were not as long, maybe an inch shorter, but I don't remember where I saw them.  Those may do away with the "old-woman's earring syndrome" that these seem to be plagued with.  Short of finding those again, the hooks on this page are the best I've seen so far!