Goal Zero Rock Out 2 Wireless Rechargeable Speaker, Grey Big Sound - DarkBass chamber allows massive airflow for deep, precise sound without the bulk. Mic Built-in - Doubles as a rugged speaker phone. Answer incoming calls from your crew. Bluetooth - Connect and rock out without wires using one-touch Bluetooth technology, and featuring a 30ft range Roomy pocket inside to store your phone, keys and other items 3Wh Li-ion battery (800mAh), weight is 1 pound