Balls are struck back and forth with a wooden cylinder , called bracciale , worn over the forearm , if carelessly played , a broken arm can result : in fact bracciale weighs 2 or 1 kilogram . Balls are struck back and forth with a wooden cylinder , called a bracciale , worn over the forearm : if carelessly played , a broken arm can result because a bracciale can weigh 2 kilograms or 1 k in different version .