World Centric® compostable clear lids for 16-32oz takeout fiber bowls are made from PLA, (polymer made from plants) . Great for warm or cold items, these lids are heat resistant up to 110F. Not microwavable. PLA products should be stored in a cool place below 110 F and out of direct sunlight. These are certified compostable in a commercial facility, which may not exist in your area.