The series of fans have following characteristics: low investment, significant ventilation and cooling effect, low noise, big air volume, small energy, smooth operation and long life, high efficiency and so on. They can be used in poultry houses, greenhouses, factory workshops, supermarkets, dining houses, stadiums and etc. they are the best cooling equipments in the large size places of the times. The shutter adopts automatic controlling equipments to let shutter blade automatically open and close by 90 degrees, thus it can reach the purpose of dustproof waterproof and effect of perfect. The quality of the products has reached the international standard.