Enjoy designing your own small portable Bluetooth audio 2.1 channel DIY project with this Bluetooth 4.1 digital amplifier board. Customize the sound with built-in subwoofer, satellite, and master volume controls. Make your own 2.1 channel small multimedia wireless Bluetooth amplifier or portable speaker with this 2 x 15W + 30W amplifier board. The board accepts 8 VDC to 20 VDC which makes it perfect for making home or mobile audio projects. Make your audio project truly portable by adding three to five 18650 Li-Ion batteries.