The Kong, Small Stuff-A-Ball is made of Durable Rubber. It has 16 Vertically Grooved Treat Slots w/Treat Grip Ridges plus a Hollowed Core giving you an outstanding Treat/Dental Work Out System. This Ball is extremely durable,a practically indestructible dog toy. Note: Aggressive chewers will eventually rip apart just about anything) also select the FREE Recipe book if desired with your purchase(while supply lasts)