The Endura Jars come with a screwtop PP lid to ensure perfect airtightness. Oven proof, freezer proof, and extreme temperature resistant these jars can be put straight in the microwave (without lid) to freshen up snacks, used to freeze purees and then thawed in the microwave before use, and of course, to store regular food items like pulses and grains. No matter what you use the Endura Storage Jars for, your food will stay 100% pure and healthy.