1>plug and play 2>RoHS CE compliance 3>Ultra high ... This allows you to simultaneously access to speakers and headphones (both two-channel stereo) and freely switch between achieving this. Quality ... insert MP3,,CD, MD,,walkman,,computer, audio output port, and speakers or headphones,then this two output ports can access. ... as long as you can turn off the speakers, and facilitate the port! 5521 DC cable