It is beautiful shape, compact structure, disassembly and maintenance easily. Impeller blades are former multi-wing.Impeller material is disposaled by zinc orHigh-quality galvanized copper.The impeller blade is pass a strict static and dynamic balancing correction and strength test. L-03 .L-064-type impeller made by stamping rolling.The chassis are wholely casted by aluminum. L-08 ... L-11-type impeller is weld structure.Chassis is welded by high-quality steel plate. Filter is filtered by non-woven,for replacement eazyly and guarantee trasport clean air.