The axial fan, the function of which is similar to a propeller, moves the air axially, parallel to the revolving motor shaft. The ebm-papst external rotor motor is integrated directly into the axial impeller, forming a compact axial fan unit. Moreover, using GreenTech EC motors also enables precision control of the air flow – they are available with tacho output, linear or PWM input, bus-connectable interfaces and many other features. They are usually installed with wall rings in short or long bell mouths.