World Centric, 10x7.5" clear lids for 3-compartment fiber containers are made from PLA, (polymer made from plants). Great for warm or cold food, 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.