Coffee warmer can keep your coffee at the most suitable temperature for drinking. safe and convenient design: the coffee mug warmer uses a tempered glass heating plate with a waterproof design. the heating plate diameter is 3.4 inches, which fits most size mugs. get the best coffee drinking experience: it is highly recommended to use flat-bottomed, thin-walled glass, ceramic, stainless steel and other cups with good thermal conductivity. the best gift choice: the exquisite packaging is very suitable as a gift. it is the best gift for your family and friends on occasions. more energy and power saving 16w heating