Features: The ultimate interactive toy for pup development and solo play Featuring a barrel shape-made of strong natural rubber Perfect for rolling and paw-pushing-and a trapped Tennis Ball All Tennis Tumbles include an extra 4-Pack of Tennis Balls for more Specs: Tennis Tumble: Natural Rubber Tennis Balls: Natural rubber core, pet-safe poly felt exterior Length: 3.86" Width A: 2.56" Width B: 2.48"