Features Made from High Quality Materials: Cutting Edge insulated bottles are made from 100% Food-safe 304 grade stainless steel. Rust-Free and Portable: The easy to use flask features a rust free condensation resistant body with a sling cover for added durability and portability. Leak Proof: The flip lid with a BPA free leak proof cap can be used as a cover making it ideal to store beverages for work picnics or day long trips. Double-Walled Insulation functional design with a double-walled insulation ensures minimal heat loss and keeps the content hot or cold for up to 24 hours.