Come and see our amazing products. The USB heating constant temperature coffee cup holder is made of iron box aluminum. This is specially designed for flat-bottomed cups, ensuring that the bottom of your cup is in full contact. The diameter of the heated coaster is about 4.06 inches and the thickness is about 0.63 inches. We welcome customized logos, please contact us. Pls confirm with us about the packing info, stock color and exact production time before placing your order.