Superior performance, a sleek silhouette and an extensive collection of beautiful designs sets S'well apart. Our signature Therma-S’well® Technology is designed to keep beverages colder or hotter, longer than all the rest.... Therma-S’well® Technology with triple-layered, vacuum-insulated construction designed to keep beverages colder or hotter, longer than all the rest. 18/8, food-grade stainless steel. Condensation-free exterior that won't sweat in your hands or bag. BPA/BPB free and reusable Hand-wash only