Try something a little different for those determined chewers. The Ultra Sub™ toy features knobbed nylon “buns” sandwiching rubber spacers and 2 ultra-thick treat rings. These treat rings are 4x thicker than our regular Busy Buddy® rawhide rings. The rings spin on their posts, allowing very little surface area for your dog to grip. This difficulty combined with the ultra-thick rings means this toy will hold a dog's interest for an ultra long time.