There are two kinds of car subwoofers. One is 12V power supply, which can be directly connected to the cigarette lighter or battery of the car. If you want to use it at home, you must use a transformer to convert 220V into 12V. The other one uses 220V electricity, which can be used directly at home, but when it is used in the car, you need to use the on-board inverter to convert the battery's electricity into 220 V. You can buy it according to your specific needs.