SUNMAY Mini Portable Wireless Power Bank Bluetooth Speaker Hook Round Loud Usb Flash Drive Play 2.1 Hi-Fi Super Bass Resonance Dual 5W Drivers 3.5mm Audio Port Compatible Outdoor Sport Bicycle Black Power bank function WHEN POWER ON.Built-in 2000mah rechargeable battery for up to about 10 hours of playtime.What'more,WHEN POWER ON,it can also be used as power bank to charge your cell phones. All area coverage. 360 degree no dead ends playing dive you into the sea of beautiful melody. Enjoy the two-channel stereo Bluetooth 3D surrounding sound,via 5W+5W speakers. Hook design,free to carry.You can hang it together with your bag,bicycle,or your body,hanging on wherever can be "hooked" . Ideal for hiking,traveling,cyclingfishing. Support many music formats while TF card or U disk playing,including MP3,WAV,WMA,APE,PLAC.This speaker allows you get rid of the worry of just MP3 and WMA format restriction. U disk playing. Most speakers do not support the U disk playing, only TF card playing and AUX playing.