The NA-SC1 Sx2 is a set of two NA-SC1 3-way splitter cables that can power and control three fans simultaneously from a single fan connector. If the splitter cables are connected in series, a total of 5 fans can be operated and controlled simultaneously. In addition, the NA-SC1 cables send the RPM signal of the first fan back to the fan connector so that PC mainboards and other fan controllers can read the fan speed. The 4-pin connectors of the NA-SC1 are provided with a special notch to prevent misalignment and are compatible with 4- and 3-pin fans. While 4-pin fans can be controlled with PWM, the rotational speed of 3-pin fans can be controlled by voltage reduction. Careful! Some PC mainboard connectors are only designed for use with 1 A (12 W) (refer to the motherboard operating instructions for more details). When using the NA-SC1 in PCs, please ensure that the total current or power of the fans does not exceed this value.