Normal. The blue light of the 55-degree constant temperature coaster lights up, indicating that the heating work is started, and the heat is obviously felt by hands near the surface of the electric coaster. Warm coasters are heated and insulated coasters, which is the working principle of electric heating. They are used to place cups, teacups and other utensils, protect the desktop, so as to put tea, drinks, milk and so on. Not easy to cool.