Stainless Steel Outer And Inner. Double Wall Construction For Insulation Of Hot And Cold Liquids. Vacuum Insulated. Screw On, Spill-Resistant Lid. Wide Mouth Opening. Keeps Drinks Cold Up To 24 Hours And Hot Up To 12 Hours. Lids Packed Separately and Unassembled. Meets FDA Requirements. BPA Free. Hand Wash Recommended.