In Asia,there are special competitions where kites have complex designs and equipped with instruments such as whistles that make musical sounds as the wind blows through them. Although all kites have a similar structure ,the variety of shapes is almost endless. The size of the kites also varies greatly -some are so large that several people are needed to control them. Kite-fighting contests are also held,in which competitors use their kites to attack and bring down their opponent's kites or cut their strings.