New at the Sigma R17 are the axial fans that keep cool the heatsink. These fans are powered at 12V, and they have been carefully selected to reduce the noise level. This however does not harm the airflow. These new axial fans will only be activated if the temperature of the hotend is above a certain threshold. This is being monitored by a redesigned PCB back in the carriage.
The Smart Fan kit is a kit that gives your Sigma the same qualities as the new Sigma R17!