Monster BTW218 Tower of Music 20-Watt Portable Wireless Bluetooth Speaker with NFC and EZ-Play Speaker Power and Features: 20 Watts, with (1) 3 inch front-firing Full-Range speaker and (2) 2.5 inch side-firing tweeters in addition to (2) 3 inch side-firing passive radiators. Connectivity: Connect wirelessly via Bluetooth or NFC technology if your device is capable from up to 30 ft. away. 5.8Ghz Technology which allows you to connect multiple speakers (up to 8) via the built-in EZ-Play Technology. Aux-In: Allows you to connect your device with an Aux Cable. Hands Free Calling: Take a call with the Built-in Mic on the Speaker. Portable Battery and Power Bank: 2200mAh lasts up to 8 hours on a full charge, without being connected to an AC outlet. Charge your mobile device via the on-board USB charging port.