Beware of answers that just say 'standard 3.5 mm'... there are more than one 'standard'. This headphone has a microphone, so it needs / has four wires that go to the plug. The plug is a 3.5 mm TRRS (translation: tip, ring, ring, sleeve). It is the usual plug that fits 3.5 mm jacks on devices that use / need an input from a microphone... such as a cellular phone. A device that is only a 'player', only outputs stereo audio, uses a 3.5 mm TRS (tip, ring, sleeve) plug with only three wires. To use this headphone with a device that has a stereo audio output jack you would need an adapter from your four wire plug (TRRS) to a three wire plug (TRS). No worries... they are readily available. BTW There is also a two wire 3.5 mm plug (TS) that is used on monaural audio connections... you might see one on a (rare) 3.5 mm input jack for a microphone.