SAMSUNG's Portable Bluetooth Stereo Speaker allows you to bring Hi-Fidelity audio virtually anywhere. Features include crystal stereo sound with powerful bass reflection, a built in microphone for use as a portable speakerphone and is magnetized which allows the unit to adhere to most metal surfaces, giving it the ultimate portability! The CK811 also has double power supply ( Includes Travel Charging Adapter and the internal Li-Polymer rechargable batteries). Fully charged, the CK811 provides up to 5 hours talk/play time and up to 27 hours stand by time. Other functions include play/pause, forward/backward, and volume control key buttons. Compatible with all SAMSUNG and non-SAMSUNG Stereo Bluetooth enabled mobile phones, Bluetooth MP3 players, CD players, portable DVD players, and wireless audio devices supporting 3.5mm stereo jacks.