The Klean Kanteen Vacuum Insulated Classic water bottle combines the original, iconic, Classic bottle with high-performance, double-wall vacuum insulation to create a highly versatile bottle. The Insulated Classic water bottle was designed with high performance in mind, keeping beverages hot for 30 hours and iced for 100 hours (64oz size), that's over 4 days! Crafted from high quality, durable food grade 18/8 stainless steel with a wide 1.75 inch (44mm) opening fits ice, is easy to fill, pour and drink from. Electropolished interior and rounded corners make the Vacuum Insulated Classic bottle easy to clean and maintain. All Klean Kanteen products are made using safe healthy materials. Hand washing recommended.