The audio input port can input the audio source of other devices into the mini stereo. Usually, the mini stereo with recording function has this interface. In addition, the audio input interface can be used to play the sound of other audio sources through the mini stereo. A common audio input interface is the RCA port, 3.5mm plug and 6.35plug .RCA is the English abbreviation for Lotus socket. It is not designed for which interface. It can be used in audio or in ordinary video signals. It is also a DVD component (YCrCb) socket, but the number is three.The 3.5mm plug refers to a coaxial audio plug with a diameter of 3.5mm. It is a connector commonly used to connect audio equipment to transmit audio signals. The headset is divided into three layers of stereo sound. we can do the OEM AND ODM,Any need, please contact with Ms Dai, email is sales@huayanelec.com.