Kinetic Go Green GlassLock is truely unique and innovative. The tempered glass is stain resistant, durable and safe. It is airtight/watertight thanks to silicone seals on the lids that keep foods safely locked inside. GlassLock is microwave safe, non-toxic and non-reactive, ensuring nothing transfers into your food while reheating. You can take it from the freezer to the microwave with no concerns. GlassLock is fully FDA approved.