HYDY vacuum thermos series observes stringent quality control in line with the Swiss SGS safety standards. It is made using advanced 18/8 (304) stainless steel food-grade, non-BPA (BPA free) and other harmful substances, it will not have any chemical change, is easy to clean and more resistant to corrosion, allowing you to drink healthy water without worries. The double stainless steel bottle is designed for 12 hours of hot thermal insulation and 24 hours of cold thermal insulation, no matter in what kind of environment.