Chuckit!® Tennis Balls are made of high-quality materials and specifically designed for the game of fetch. Constructed of natural rubber it features an extra-thick rubber core and durable material that floats in water. The bright colors provide improved visibility when playing with your dog and help to prevent the ball from being lost. Use alone; or with your Chuckit! Launcher (sold separately). These high-bouncing tennis balls are available in sizes small; medium; large; and with one; two; and four-pack options. PRODUCT NOTE: Supervise playtime and know your dog and choose the appropriate size and type of toy to prevent choking or other harm. Inspect this toy regularly; if the toy is damaged or if parts become separated; remove the toy and parts as injury may result. No dog toy is indestructible; and every dog interacts with its toys differently. Supervised play will go a long way to helping your dog's toys last longer.