The second you splash some milk into your coffee is a very special, beautiful moment in time — and using a clear mug gives you an unobstructed view of the rich, caramel-colored swirl as the contents blend and harmonize. This one by the thoughtful design experts at HAY is made from a durable borosilicate glass that's great at retaining heat, with a a simple lip and slim handle that keeps your fingers far from the heat.