Altec Lansing inMotion Portable Audio Speakers For Mini Four custom-designed neodymium 28mm micro driversMaxxBass technology for quality bass without a subwooferBuilt-in docking station charges and plays iPod with dock connectionAux input supports all portable music players with 3.5mm mini-jackFolds to be 7" W x 4 7/16" H x 1" DUses 4 AA batteries (not included) or AC powerIncludes universal power adapter