Efficient low noise heatsink and radiator cooling with pwm control the wide body low pitch blades of the sp120 fans combined with the custom housing provides outstanding static pressure and airflow through heatsinks or radiators with rubberized corners a quiet and reliable advanced hydraulic bearing and pwm support for increased fan speed control the sp120 truly is the strong silent type included in the box are the three user replaceable colored rings in red blue and white so you c