The aerodynamically shaped impellers of JFUO/ JFRO/JFUC/JFRC axial Jet Fans are manufactured from injection-moulded aluminium alloy, the pitch angle can be adjusted during standstill. Impellers are balanced to grade G6.3 according to VDI 2060 / ISO 1940-1:2003. The backward-curved high-efficiency centrifugal impellers of JFC Jet Fans are made of welded aluminium sheets and are balanced to grade G2.5 acc. to VDI 2060 / ISO 1940-1:2003.