A baseball bat is a smooth wooden or metal rod used in the game of baseball to hit the ball after the ball is thrown by the pitcher. It is not more than 2⅔ inches (70 mm) in diameter at the thickest part and not more than 42 inches (1067 mm) in length. It usually weighs no greater than four pounds (1.8 kg). The batter uses the bat to try to hit a pitched ball so that he may run around the bases and score points.