Bluetooth Speaker Adapter with Lithium Battery: Portable, Bluetooth Music Receiver with Stereo Output (3.5 mm) for Home and Auto Stereo Systems-- By CyberTech Works with the speaker or home/car stereo system which has 3.5mm line-in jack Play music from Bluetooth A2DP enabled mobile phone and other Bluetooth A2DP audio devices. Build in battery, up to 12 hours working time, 230 hours standby time. Compact design Sold exclusively by Cybertech with 1 year warranty