Sold as a 2-pack, these adapter cables allow you the ability to connect 3-pin and 4-pin PC fans to a mini 2-pin fan header. This cable is ideal for aftermarket fan replacements in many devices such as power supplies, networking equipment, 3D printers, etc. It is important to verify that this 2.5mm pitch XH-style 2-pin connector is compatible with your device as there is also a less common 2.0mm pitch PH-style 2-pin connector found on some devices which this cable is not compatible with. A quick visual check confirming that this cable has the same 2-pin connector as your original device will be sufficient. On the mini connector side this cable is wired for Pin 1 as the positive voltage (red) and Pin 2 as the ground (black). Some users may find that their device does not use this wiring arrangement and will have to swap the wires. Pull back the sleeving and use an instrument (small flathead screwdriver, pen, etc.) to release the pin retention clips and swap the pins.