The Marucci CAT9 Baseball Bat is a high-quality metal alloy bat with a 2 3/4 inch barrel diameter and a 31-inch length, making it suitable for youth baseball players. This USA Baseball approved bat features an anti-vibration knob for a comfortable grip and balanced swing weight of 28 oz. The CAT9 series is a popular choice among young baseball players looking for a durable and effective bat.