One Divided into Two: one 4 pin fan connector a wire that sends the RPM signal to the motherboard connector for synchronizing the fan speed with the other fan; and one 3 pin fan connector omits the RPM signal pin for tandem fan speeds with both fans Keep Same Speed: MOBO 4-Pin receptacle connects to the 4-Pin header on the motherboard and splits the signal to 2 PWM fans; Fans can spin at the same speed using software from a motherboard equipped with PWM control. The fan adapter is compatible with 3-pin and 4-pin PC fans. Increase Airflow: This PWM fan splitter cable connects 2 computer case fans to a single motherboard fan header to increase airflow in your computer case, adding ventilation and regulating the fan speed in a computer case for a gaming rig. High quality: The cooling fan cable is covered with fine nylon for long-term years' use. High-quality high-density black sleeved cable, 24AWG, and the length is about 10.6 inch (27cm).