Shaped like a kid's toy jack, this makes a sort of "click ziiiiip" noise when the dog touches it. Even after repeated use, the noise was less annoying than the others I tested. It will move in unexpected directions because of its uneven shape, and dogs can tug on it. It's big enough at 7 inches that two dogs can play tug with it.
My dog Brownie's response to it: He was afraid of it, he backed up from it and barked at it. I am still trying hoping he will play with it someday.