Mustard USB Cup Mug Warmer Coaster- Donut Freshly Baked (M11011B) Plastic Donut USB Cup warmer with Metal heat element Measures 3.98 x 3.58 x 0.28 inches Plug and Play USB Donut coaster which operates up to a temperature of 50c / 122 F to help slow the cooling process of your drink. Also features on/off switch Windows PC and Mac compatible USB accessory This is not a toy. Do not eat. Gets hot during use, handle with care.