For those of you who have larger Yorkies, I highly recommend the Wiggly Giggly mini ball made by Multipet. It's bigger...4.5" but Tuffy is 8 lbs & he can pick it up no problem. We got ours from PetEdge but lots of other places carry it too.
It doesn't have the typical squeaker in it but a baffle like device that makes it "giggle".
It's a ton of fun!
Here's the Google search page for it so you can see it for yourself
Wiggly+Giggly