50'' ehxaust fan, the characteristics are as follows: 1) high overall pressure 2)large blowing rate 3)lower noise and power consumption 4)Stable operation, long duration. 5)outer size can be: 1380x1380x400mm,1220x1220x400mm, 1100x1100x400mm, 1000x1000x400mm, 900x900x400mm, 820x820x400mm and so on.