The Deluxe Sound Sensor Light Bar is like a portable version of a nightclub lighting fixture! 9 multicolor LEDs flash outward from the center in reaction to music or other sound input. The louder the sound provided, the brighter the LEDs light up. An adjustment wheel allows you to customize the light show for different sound environments. The Light Bar can also be set to an automatic mode that flashes the 9 LEDs in different patterns automatically without needing sound to activate. This item makes an impressive effect yet is small enough to be able to carry to a club and play with while dancing. Measures 10.25" long, 2" wide, and is 1" deep not including the battery compartment. The battery compartment actually makes it easy to grip in your hand or set on a table. The battery compartment is centered on the back and measures 5.5" long and 1" deep. Uses 4 AA batteries (replaceable) or can be powered via an optional AC adaptor.