Etree Bluetooth Wireless Receiver Adapter for Headphones Black Works with the speaker which has 3.5mm line-in jack and play music from Bluetooth A2DP enabled mobile phone and other Bluetooth A2DP audio devices; 3.5mm line-in jack allows you to play other external audio sources, such as MP3, MP4 etc; Bluetooth specification: Bluetooth V2.0; Bluetooth profiles: A2DP and AVRCP; Compact design and high quality