Rubber gives it strength, bounce and a soft texture. The unique open design allows you to stash small treats or kibble inside for hours of entertainment for your dog. This is the top selling dog toy in the line, it is non-toxic, durable, rubber and super-stretchy. A do-it-all multipurpose dog toy! It's a fantastic treat ball, wonderful training aid, great for fetch, toss and tug, chewing and teething.