These TrueSeal handy BPA-free glass containers are stackable and perfect for storing leftovers, salads, marinating meats and reheating food right in the dish. Tempered glass for superior durability is freezer, microwave, oven and dishwasher safe. Comes with plastic lids that clean up quick in the dishwasher. Lids are not oven safe. Made in the USA. These TrueSeal lids are the only product out of 28 tested by the Good Housekeeping Research Institute that earned a perfect score for air tightness. lid features a transparent window for easy viewing-lids are not oven safe but can be washed on the top shelf of your dishwasher"