For Music, Smartphone, and more Energizer BTS-104 is a portable bluetooth speaker with extra power for your device. Built-in microphone allows you to directly answer calls or hold conference call when using the speaker. BTS-104 transmits the sound up to 10M, and also works with bluetooth connectivity, AUX, USB, and micro SD card. The portable and hangtag design makes it easy to carry. The Energizer PowerSafe Management guarantees against short circuit, overcurrent, overcharge and overdischarge for your power bank and devices.