The added Max Glow technology quickly absorbs light from any source and glows for up to 30 minutes of playtime after dark. The squared corners cause the ball to bounce every which way when thrown. Made from durable rubber. Easy-to-clean. This high-bouncing, glow-in-the-dark erratic ball is available in size medium, sized just right for use with your medium Chuckit! Launcher. Chuck It Glow Ball Erratic Dog Toy is approximately 6.5 cm in diameter.