Toppl® is perfect for small dogs, big dogs, pups, old souls, clever dogs and well ... DOGS! Toppl traps treats within its inner ridges and then tips and topples over to keep dogs entertained and mentally challenged. Interlock the two sizes (each sold separately) to change up the challenge. As your dog gets more familiar with Toppl's treat hiding and puzzle attributes, you will be able to increase the difficulty of this toy so they stay engaged longer.