Smart Warm Coaster BWD-55A White Mug Warmer. Electric. Clean and working well There is a button on the bottom that acts as a safety. Unless a cup is on the coaster, it won't depress that button and will not warm up. The thermostatic cup can keep your drink warm almost all day. When you need it, a drink of the right temperature is ready. No need to wait, no need to reheat your drink. Microgravity technology, put the cup in the automatic heating zone, 19w low power heating. Small size, only the size of the palms, easy to carry. It adopts waterproof design, easy to clean, safe and reliable.