Features: Model: T20 Built-in Rechargeable li-ion Battery. Supports phone/ Laptop/ Tablet/ TF Card ( Micro SD) Expanded BXS (Bass Xpansion System) drives a fuller, richer low-end response. New larger 45mm driver delivers precise high for superb sound. Support 99% of Bluetooth-enable devices,such as mobile phones, laptop computer etc. How to use: Mode Key: Allows user to switch to bluetooth/ USB/ TF Card/ FM Radio Volume down button: Turns volume down when long press/ Last song for short press Volume up button: Turns volume up when long press/ Next song for short press Pause/ Play button: Press twice to ring up a call/ Press once to answer a call/ Long press to cancel pairing under bluetooth/ short press to search station in FM mode.