Unique and innovative, Glasslock's tempered glass is stain resistant and durable as well as healthier and safer for your family. Lids lock with green silicone seal, making the containers airtight and watertight, keeping the foods and flavors locked inside. Microwave-safe, non-toxic, and non-reactive, storage unit's seal ensures nothing transfers into your food while reheating. You can take it from the freezer to the microwave with no concern. Environmentally friendly plastic lid and silicone seal. Not suitable for oven or direct heating. Remove lid before using microwave or reheating.