These 4 oz compostable portion cups are made from polylactic acid (PLA), which is derived from corn grown in the USA. This item is certified biodegradable by BPI. It is freezer safe and best used for beverages below 120 degrees Fahrenheit. Not microwavable. Cup printed for customer awareness: “Made From Corn – Certified Compostable In Industrial Facilities. Store out of direct sunlight in a cool place.