Arctic 4-Pin PWM Gehäuselüfter Splitter Kabel für 4 x PWM Gehäuselüfter - ACCBL00007A
The rpm of the first fan socket will be read out and fed back to your system. Even if you don't have enough fan headers on your motherboard, the 4-Pin PWM Fan Splitter Cable allows you to connect up to four case fans to a single header.