The fan is made completely with polyammide. The blade can be oriented from 20° to 50° to obtain different air flow rate. The adjustment is made quickly without remove any part of the fan and any safety parts. The adjustment is made by a special tool on the fan-hub. Clock-wise rotation increase the blade angle and counter clock-wise rotation cause a decrease of blade angle. Four complete turns of the tool can change flow rate from minimum to maximum level. There are two kind of blade in order to obtain clock-wise rotation of the fan or counter clock-wise rotation. The standard color of the fan is red, other colors are optional.