designer's own words:i.cup combines two materials for two comforts. Porcelain for a smooth and gentle surface. And PCM for enduring warm drinks. PCM is a synthetic material which saves excresent heat from its surrounding. When the surrounding cools down, PCM releases the saved energy to heat up again.Thereby it´s possible to heat up air, your body or food for instance. This technology is already used for snowboard jackets. You are skiing down the hill. The microscopical small capsules save the heat your body is producing. Later when you´re going up the hill with the lift, the capsules give the energy back. So you don´t cool down. That´s the way we do it with your coffee. i.cup saves energy from a liquid. Chemically it´s possible to define the efficiency exactly If the desired temperature is reached, the PHASE CHANGE MATERIAL begins to heat up your drink. The liquid doesn´t cool as quickly as normal. You can read your newspaper or chat with friends -and your cappuccino? -stays hot.