Both the interior and exterior layers of this cup are made of stainless steel with a vacuum insulated layer, suitable for containing any hot or cold beverages and keep their temperature for a long time. It is safe and corrosion resistance, won't leave any metal taste in your mouth. The slim, lightweight design also makes it easier to transport to and from the gym, work or home. It fits most car cup holders. It's portable, convenient, simple and beautiful. It also prevents water from flowing too fast and chocking water, reduces spills, especially on the bus or walking. It is really perfect for coffee, tea, cold water or other beverage you want. It's the best choice as a gift for family members or friends. Custom logo is available.