Also available as a pack of 75, SKU - SBL-CS-16-P. World Centric compostable clear dome lids for 16 ounce salad bowls are made from PLA, (polymer made from plants). They are suitable for cold foods, freezer safe. Not microwavable. PLA products should be stored in a cool place below 110 deg F and out of direct sunlight. These are certified compostable in a commercial facility, which may not exist in your area.