This is a great double-wall glass mug.  I use it every day for both hot and cold beverages.  No more coasters required as the double wall glass prevents condensation to form on the outside.  This double wall glass mug from Bodum comes with a special silicone base - water does not get between the glass layers and the mug can also go into the microwave safely without breaking.  Great for heating up milk or reheating beverages.  The only mug I use nowadays.