100% pure High-quality food grade 18/304 stainless steel on both inside and outside walls non-leaching and toxin-free The double walled vacuum insulated exterior will keep your drink the same temperature as long as science will allow. 1.#304 food grade stainless steel construction 2.vacuum insulation 3.Copper plated inner wall 4.Seamless structure on side and bottom of inner wall 5.Hot 8 hours 6.Cold 16 hours