These are standard dog tennis balls that can be used to replace the original chuck it ball your dog immediately destroyed. My pupper takes a "you can look but you can't touch" approach to fetch, and he makes sure to pop new tennis balls because I guess they are easier to carry around in tqwo pieces.. I have yet to find a tennis ball that can stand up to his desire to destroy in 2 seconds, buthese are great for the price! I'll be purchasing more since, well, see above.