axial fan: 1.Impeller 5-sickle bladed proled die-cast aluminum impeller, sizes from 200 to 710mm, available in 60Hz and UL types, air volume from 480 to 16080m3/h. The center-plate of impellers fit areo-dynamic profile. All impellers have passed balance test according to our own standard, which is higher than national standard. 2. Bearing All bearings in cooling fans are manufactured by brand name companies of Japan. These ball race type shaft bearings are hermetically sealed, pre-greased and self-aligning. Under, normal duties, these bearings are service free. 3. Motor The motors inside are all newly external rotor motor with thermal protector inside and this insulation class of motor is F. We can also supply motors in other brand as client appointed. 4. Feature For installation in equipment with short bell mouth, high flexibility by variation of blade angle and speed of motor, available in both airow directions as well as 60Hz. 5. Application Ventilation, air conditioning, heating technology, drying, cooling, agriculture. Highest quality and novelest design, that's our goal. Our Guarantee: 101% satisfaction on our quality and service. If you have any problems, plz contact us, we will solve it for you within 24 hours. If you have any suggestions, plz tell us, for our further improvement, thank you so so much!