Set of 4 stackable, double-walled vacuum-insulated stainless steel tumblers (450ml) Double-Walled Vacuum Insulation: This special design provides superior heat retention compared to single-walled tumblers, while remaining lighter than traditional thermoses. The double-wall structure effectively slows down the temperature loss of your beverage, perfect for hot water, juice, cocktails, or iced drinks, and reusable for extended periods. Stackable Design for Easy Storage: This four-cup set stacks neatly for space-saving storage in any cupboard or drawer. Highly portable, ideal for travel, camping, beach trips, and picnics. Safe and Eco-Friendly: Made from 100% food-grade stainless steel, these tumblers are rust-proof, drop-resistant, durable, and contain no harmful chemicals. They are odorless, preserving the true taste of your drinks. The smooth, polished interior and exterior are easy to clean. The reusable metal material is environmentally friendly and safer than plastic. Suitable for Children and Adults: The easy-to-grip design is comfortable for both adults and children. With a modern design and craftsmanship, these tumblers offer advantages over traditional plastic or glass drinking cups, making them suitable for any occasion and perfect for gifting. Easy to Clean: These durable tumblers are dishwasher safe. The specially treated interior and exterior resist water stains and are very easy to clean. They are built to last and can be reused repeatedly after cleaning.