Stainless Steel Outer And Ceramic Inner Liner. Inner Ceramic Coating Eliminates Metallic Taste And Protects Stainless Steel From Staining. Ceramic Coating Allows For A More Robust, Natural Flavor. Double Wall Construction For Insulation Of Hot Or Cold Liquids Liner. Vacuum Insulated. Snap-On, Spill-Resistant Thumb-Slide Lid. Meets FDA Requirements. BPA Free. Hand Wash Recommended.