This unbreakable vacuum insulation is made of high quality stainless steel, very sturdy and dishwasher safe. Double Wall Design: The double wall structure works great for hot or cold beverages without transferring the heat or cold to your hands. They have a brushed finish on the inside. It is well made so no sharp edges and you can easily drink from it. Perfect for kids: The handle is easy to hold and perfect size for kids to use around the house and for camping, picnicking and traveling.