Wheat Straw Polypropylene, Double Wall Construction For Insulation Of Hot Or Cold Liquids, Screw On, Spill-Resistant Lid With Matching 9" Buildable Straw, Composed Of Reclaimed Stalks From Wheat, Harvested Wheat Is Renewable And Sustainable, No Indication Of Extractable Gluten In Testing, Meets F-D-A Requirements, BPA Free, Hand Wash Recommended