Portable Wireless Bluetooth Stereo Receiver for All 3.5mm Audio-in Speaker Systems Such as Portable Speakers, Headphones, Home stereo, Car Music Sound Systems (Black) Adopt Bluetooth V2.1 + EDR technology with superior wireless performance Supports A2DP, enabling your audio device to transfer stereo audio wirelessly; Supports AVRCP for remote play/pause. Turns any ordinary speaker system (with 3.5mm audio-in jack) into Bluetooth-enabled music streaming solution with no additional drivers required. Embedded Li-ion battery allows for convenient recharging;Energy saving capability: powers off automatically if pairing fails for over 5 minutes. Internal current-limiting circuit allows charging with any adapter whose output ranges from 5V/100mA to 5V/2.1A. (ADAPTER NOT INCLUDED)