1.ce certificate 2.galvanized frames 3.big air volume 4.six stainless steel blades 5.shutter open/close automatically Product features Fan Frame: made from highly galvanized steel sheets in order to assure highest strength and strong resistance to corrosion. Blade: 6 pieces stainless steel blades and the fan has all passed the experiment of homeostasis with big air volume, without deformation n, ...