iRiver BTS-SD2 Portable Bluetooth Wireless Dual Stereo Speaker Sound Donut version 2 - White Class 2 bluetooth v2.1+EDR/Profile A2DP, AVRCP, HFP, HSP Battery 3.7V 720MAH Lithium Polymer Rechargeable Battery External interface micro 5 pin USB connector for charging Stereo Earjac (3.5mm)/Power consumption Standby Time: 450 Hours Talk Time: 11 Hours / PlackBack time: 9 hours / Dimensions 136mm X 26mm (Donut shape)