Centrifugal fans from ebm-papst are available with forward- or backward-curved blades. The low-noise centrifugal fans with forward-curved blades are also supplied with a scroll housing. The centrifugal fans with backward-curved blades are designed as free-wheeling fans and do not require a scroll housing. For the centrifugal fans with external rotor motors, the motor is positioned in the impeller, resulting in optimum cooling of the motor as well as an especially compact design. The entire product line is available in both AC and GreenTech EC technology.