Huion Rechargeable Lithium Battery 8mm Ultra-thin Light Panel Touch ADJUSTABLE Illumination USB LED Light Pad (LB4) .Built-in Li-ion Battery free your using place. You can bring the light box to everywhere; Built-in Li-ion Battery will supply power to box. .USB Mode: you can get the power from any electronic thing with USB Port, such as computer . Adjustable Brightness: Touch adjust brightness from dark to light or from light to dark . Memory Feature: this light box can memory your last brightness so you do not need to adjust the light every time. .LED light source protects your eyes and save energy.