Coolmusic BP25 Rechargeable 25 Watt Guitar Amplifier Being with 3 channels, it can input one microphone and two musical instruments or devices at the same time. Built-in rechargeable lithium battery can be run up to 4 hours when it is full charged and also can offer power to your devices. The amplifier with Bluetooth function can be compatible with phones or PC. Built-in USB charge function and MP3 input function make you listen to music anywhere and anytime. DI output allows you connect to another device, such as mixer or amplifier.