The NA-FC1 is a compact, highly flexible controller for 4-pin PWM fans that can both work on its own for manual speed reduction and also work in tandem with the automatic motherboard fan control. By adjusting the NA-FC1's speed control dial, users can either manually set a PWM duty cycle from 0 to 100% or reduce the PWM duty cycle supplied by PC motherboards in order to have the fans running slower than the automatic motherboard fan control would allow. While the brightness of the orange status LED provides visual feedback on the current dial setting, the push button allows the NA-FC1 to be switched into "no stop" mode, which prevents the fan from falling below a speed of 300rpm. Thanks to the supplied 3-way split cable and power supply adaptor, up to 3 fans can be controlled simultaneously. PWM based control While most fan controllers are voltage based, the NA-FC1 uses the more sophisticated Pulse Width Modulation (PWM) technique that allows for more efficient control and lower minimum speeds, regardless of the fan's starting voltage. Customising motherboard fan control Many motherboards provide insufficient options to customise automatic fan control or simply don't go below certain duty cycles and speed levels. Using the NA-FC1, you can lower the motherboard's PWM control curve in order to achieve truly silent operation, even with high-speed PWM fans such as Noctua's industrialPPC series. For further details please visit the manufacturer's website.