Features: Function: This cable is 5V USB port to small 3-pin / 4-pin fan cable with switch, it allows you to power most case fans by using a USB connection, 3pin or 4pin case fan power adapter cable both OK, you can turn on/off any time by switch. Connector: One is USB port, another one is small 3 pin / 4 pin case fan power adapter cable port. Cable length: about 40cm / 15.75inch. Fan must have a start voltage at or below 5V (fans with a higher start voltage will NOT work), 12V fans will be operated at a reduced 5V voltage for silent operation. You can use this line to supply power to the chassis fan by computer's USB port, or DIY the chassis fan to modify the notebook cooling pad fan. Package Includes: 1PC x Cable Specifications: Name: USB to 4Pin switch line 1 to 2 way Length: approx. 40cm/ 15.75in Wire model: 2464 22AWG Insulation material: PVC insulation Conductor specification: 17x 0.14TS Conductor material: pure copper Wire outer diameter: OD 3.5mm Rated temperature: 80 Colour: Black Interface: motherboard 4pin connector at both ends, USB interface at the other end Function: Change the chassis CPU fan B interface for power supply note: The fan must Have a Start Voltage of or less than 5V (fans with a higher start voltage will not work). The chassis fan uses this USB adapter cable, the fan speed will be reduced by 60%, It is recommended e a fan with a higher speed when using this adapter cable. Please allow 0-1cm error due to manual measurement. pls make sure you do not mind before you bid. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you