Premium 304 Grade Stainless Steel: Made from international-grade stainless steel, the Destinio thermos flask is rust-proof and ensures your beverage stays fresh and delicious. Keeps Drinks Hot and Cold for 8 Hours: With copper-coated, double-walled vacuum insulation, your drinks will stay at their desired temperature for longer. The 2-way infuser can be used with loose tea leaves, tea bags, coffee, herbs, fruits, and more, giving you endless beverage options.