DOSS Pie Portable Bluetooth speakers,Ultra Slim Pocket-Sized Portable Wireless Stereo Speakers with Dual Drivers,4W output,Built-in Rechargeable battery,handsfree,3.5mm line-in support[Blue] Full & High sound quality-Enjoy an impressively crystal clear sound quality and robust bass through dual 4W drvers & a passive subwoofer. Portable Pocket - Incredibly compact perfectly fits into your jacket pocket or small bag suitable for both indoor and outdoor exercise. Bluetooth 2.1 Technology-Connect your device in 2 seconds,compatible with all audio devices,outstanding connection range of up to 33 feet. Long playtime-Built in Li-Ion 1000 mAh rechargeable battery rechargeable battery, supports up to 4 hours playing time at the volume of 50%. Hans-free fuction-Convenient to answering when driving/travelling etc.