Monoprice 103509 Folding Speaker Dock, Black Powered by 4x AAA batteries or a 6 volt DC adapter (not included) the system plugs into the headphone output jack of your portable music device The amplifier powers the 50mm aluminum speakers with 1 watt of power more than enough to fill a small room with sound The speakers fold into each other for a compact form factor that is easy to pack into your luggage and protects the speakers from damage