Keeping You Warm on Cold Days --- The coffee mug warmer is convenient and portable. Refreshing your morning favorite mug of coffee hot at your desk while you work or keep a cup of hot tea steamy while you relax on the couch. Ideal Gift for Coffee/Tea Lovers. Thermostat for Your Beverages --- The tea cup warmer is built in thermostat for keeping your beverages (tea, coffee, milk tea etc) at the perfect temperature from the first sip to the last drop(50-80). Kindly note the desktop usb heated coaster only can be used for keep water warm, can't boil water. Safe & Durable --- The usb coffee mug warmer is made of high quality walnut wood and metal materials, heating evenly, safe and durable to use, has natural walnut wooden grain and smooth to touch. USB Port Powered --- Any device with an output 5V USB port, such as a computer, desktop, laptop, tablet, mobile power, etc. Compact design, keep the beverages warm all day long, it's a great gift for lover, dad, mom, wife, husband and all your loved ones on Valentine's day, Thanksgiving and Christmas. Suitable for Most Mugs --- The coffee cup warmer can fit most cups, such as glass cups, stainless steel cups, ceramic cups, etc. To obtain better results, we recommend using flat-bottomed glass cups or stainless steel cups. Putting a lid on the cup will also help retain heat.