I didn't have high expectations for these, but my kitten (Norwegian Forest Cat) loves them. We play "fetch" (i.e. I throw, he fetches, but doesn't bring it back), and he rolls them around on his own and wrestles with them. Really great quality and so well worth the price.
Our outdoor cats aren’t interested in toys, but the dogs fight over the balls. The balls can withstand a bit of chewing, and the dogs love throwing them around and pouncing on them (Eurasier breed). I had to order more because the balls sometimes disappear into random corners of the house and can’t be found for months, which makes the dogs visibly sad.
They’re quite big, so they don’t fit under our furniture. They’re made of wool, so they’re quiet, and not perfectly round, which means they sometimes roll in unpredictable ways—making them even more interesting for the cat. I recommend them, my kitty loves hunting them.