There are 3 small balls with sand sound inside the roller. Pets are very interested in the smell of sisal. It is cats’ favorite. The cat tried to get them out but it couldn’t. Designed especially for cats to sharpen their claws. With it, your cat will no longer scratch or damage your sofas and furniture.Just like human beings, pets like toys too. This toy can help to train and exercise its brain and sense organ and avoid the occurrence of depression even if its owner is out.