Just place the teacup or coffee cup that needs to be heated on the coaster and then plug line head in to a USB outlet and it will start to work to the temperature you want with the USB port.
Made of PVC
USB line length: 1.3 m
USB plug can be connected to the computer, charger, charging treasure
Keep your cup warm for a long time
Large imprint area
Suitable for most water cups, milk cups, coffee cups, long lasting warmth in the cold winter.