The HoMedic nature sound machine relaxes your mind, body and soul. It can be used while you"re studying, working, meditating or sleeping. This sound machine is pre-loaded with 6 digitally recorded natural sounds of ccean, summer night, rain, thunder, white noise or brook. This HoMedic nature sound machine reduces sleep disturbance and associated stress. It has an auto-off timer that you can set at 15, 30 or 60 minutes, so you don"t have to turn it off manually. This spa sound machine can be used right out of the box and doesn"t need any assembly. Its small and compact size allows easy carrying and storing. It can be powered with a battery or the included AC adaptor.