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. The product is marked at 10oz but, can hold up to 12oz.