1. Use the power from direct current batteries 9 VDC. A rechargeable.
2. Can be used with battery charger The size 9V For ease of use.
3. Raise - Lower the sound And turn off the sound by adjusting VR1.
4. You can use the speakers with headphone jack.
5. There LED1 indicator circuit.
6. Reverse Polarity Protection.
7. Dimension 4.6 cm X 5.78 cm (1.81" X 2.27").