REXSONN&reg; USB Powered Mug Cup Warmer Donut Designed Heat Insulation Pad for Tea Milk or Coffee Hot Coaster Mat - Green Excellent in Insulating: Keeps your drink warm at 50-60/120-140 so you can enjoy it all day long USB Powered : Works with any USB 2.0 port and built in battery, even be able to keep your drink warm with powerbank plugged in. Unique Cookie Design: cute cookie designed mug warmer, lightweight and portable. Easy to Keep Clean: non-stick heating element make the surface can be easily clean! Anti Slip Rubber: help settle the items, preventing drinks sliding or pouring down.