Yes, in my house, the tennis balls are tested as to how strongly thay yellow fuzz is attached...my kids will give that material(what in the heck is is MADE OF anyhow?) a run for my money...they don't eat it, but, at times, they will try to "strip it" of its lovely yellow coloring...*dang kids*..anyhow, when I notice them being that bored, I promptly remove the balls, & straight away offer something "different" to them....I'm not made of "mini kong-ball money" after all!! *sheesh!! save the rough chewing for the bully sticks or the lamb bones, would ya' please"!! *rolls eyes*LOL