The 9900 series AC Axial Fan is used when DC voltage is not available. The AC range of fans is based on experience gained from decades of development know-how, millions of units in series production and the innovation competence of a world-wide technology pioneer. They offer economic benefits whenever the air duct design can be integrated in the respective device. The fan blades are directly attached to the external rotor of the external rotor motor. This construction offers combining high performance with profitability. The AC axial fan is suitable for high air performance with moderate pressure build-up. The flow of air through the fan blades is parallel to the rotation axis. They are extremely flat and space-saving integrated motor. The AC fans with sleeve bearings are powered by Class E insulated motors. Fans with ball bearings are equipped with Class B, E or F insulated motors. Fans driven by capacitor external motors provide particularly high operating efficiency.