"Simply plug the cord, tap the switch, and put your cup on and you're ""All set."" Now the Cap warmer will keep your drink warm to the last drop. This cup warmer not only can slow down the cooling speed of your hot beverage, but also can heating up your cold beverage to 120?-140? (40-60?). The cap warmer plate has no groove, so it can fit most cups, such as glass cups, stainless steel cups, Ceramic cups, etc. We recommend using the cup with a flat bottom for better heating results. Suggested adding a lid to cover the cup or mug will also help retain heat. An essential desktop gadget for home, kitchen, office, party, or outdoor activities. The perfect choice for keeps your body warm all day, a great helper to create a better life as well as an ideal Gift for all occasions. This is not a toy. Do not eat. Gets hot during use, handle with care. "