Can anyone identify this cat toy?

I've been looking all over for them but don't remember what they're called. My father picked up a couple of packs for me and my cats adore them. I'm down to one, and have checked pet store after pet store - no luck. And my dad ALSO doesn't remember where he got them...

    
Thanks!!

Yes, they're called Cat Crazies and you can get them on Amazon.
They use to be one of Ritz' favorite toys, now I think she's a little afraid of them. They work best on tile, not carpet.
I think I bought them at PetSmart.

Oh. My. God. THANK YOU!! I love the Internet. I  have been trying to search for these online and couldn't, partly due to lack of keyword ideas. "Little plastic ring thingy" +"cat toy" and the like did NOTHING. THANKS!!!

If you want to save a few bucks, my cats actually like milk/water jug rings much better than these. Sebastian's favorite is the blue ring off a Hellman's mayonnaise jar (it's a larger ring). 

Yes, I know what you mean.
Luckily I remembered the name, which I thought was unusual ("crazies").