Thai boxers are graded from fly weight to heavy weight, but welter, middle and heavy weight fights are rare. As with other styles of boxing, a referee controls the fight inside the ring and there are two judges who keep score outside the ring. At the opening sound of music, the two boxers in the ring will perform a short ritual of 'Wai Khru' (paying homage to the teachers) and this quite often proceeds to a staging of the Four-faced Brahman dance which symbolizes four virtues: compassion, temperance, prudence and justice. Upon the completion of the prefight rites, boxers return to their respective corners to have their ceremonial headband removed and receive the last prefight instruction from their trainers. At the signal from the ring referee to fight, both boxers go into action. They fight 3 minutes rounds alternated by 2 minutes rest periods