Mini design, do not take up space. Perfectly suitable for personal use, you can use it on office desk, in the car, or on the night stand of Baby Room, Living Room, Bedrooms, Dorms or take it to yoga clubs, fitness center where close to your body. Smooth moisture easily penetrate the skin surface, direct to base layer, keep the cells full of water. USB Plugged in Power Supply: this unit (no battery inside) powered by usb cable plugged into power supply .