A 3.5mm (1/8") 4 pole cable delivers what a standard 3 pole cable does stereo (left/right speaker} & return signal (or ground} as well as a 4th pole.  This 4th pole is used for a microphone (such as on gaming headsets), video or control signal, depending on the equipment it is plugged into.  

A 4 pole cable will also work on standard 3 pole devices.

The "Slim Connector Design" is useful for equipment where a standard connector is to thick.  This can be a cell phone in a case or other tight places.

Fits all standard headset, speaker and auxiliary (AUX) ports with a 3.5mm (1/8") stereo connection.  Also known as a TRRS (Tip, Ring, Ring, Sleeve) referring to the connections on the connector used for the stereo connections, ground and video/control/microphone.

The cable has a 2.8mm OD Black PVC jacket with fully molded construction and nickel-plated 3.5mm stereo plugs.

With a 26 gauge stranded copper center conductor, low-loss 95%, and 99.99% pure oxygen-free copper wire, this is an excellent choice for your audio interconnection needs.