Revolutionary design makes these toys bounce unpredictably in every direction. Stuff Senior Kongs® with treats for even more fun. An ideal way to stimulate play and exercise in older dogs. Soft rubber is great for light chewers and gentle for older dogs’ sensitive teeth. Non-splintering, non-abrasive, and does not get sharp when chewed. Toys measure Small-2 3/4", Medium-3 1/2", or Large-4 1/4". Made of thick, puncture-resistant rubber. Dome shape is hollow in the center.