Roller Ball by Tolo contains a smaller ball within that makes a pleasant rattling sound as infants play with it or use it to encourage baby to crawl or walk by rolling it around the room! Made of bright, durable plastic. This brightly colored, eye-catching rolling ball has a smaller ball inside of it. Inner ball makes a pleasant rattling sound. Shake, rattle, and roll! This brightly colored plastic rolling rattle resembles a ping pong ball enclosed within a whiffle ball. The inner ball makes great rattles as it rolls and bounces within the outer ball. With plenty of slots on the outer ball for little fingers, baby can easily grasp the lightweight unit and shake or roll it. Great for crawlers who will enjoy pushing and chasing this seemingly live rattling wonder around the room!