Its form is like the sound box of accordion, be double deck, facilitating heat insolation, free retractility, make no matter be,fluctuate to close, very easy.

• 其形如手风琴的音箱，是双层的，便于隔热，自由的伸缩性，使之无论是左右开合还是上下开合，都十分的轻易。