iBomb(TM) EX350 High Quality Wireless Bluetooth 3.0 with 3.5mm AUX Input, Microphone, Micro SD Card Slot Include for MP3 Function, Rechargeable Super Bass Sounding Stainless Steel Mini Speaker (Silver) Built in lithium battery voltage: 3.7V Battery Capacity: 400mAh Frequency Response: 60Hz - 18KHz Working Range: Up to 10M Play Time: 6-7 Hours