This product is a replacement stopper for Stanley Classic Vacuum Insulated Wide Mouth Bottle Thermos. It is made of high quality food grade silicone, which is safe, non-toxic, and durable. The stopper has a good seal, and can effectively prevent the leakage of hot liquids. It is easy to install and use, and is compatible with a wide range of Stanley Classic Vacuum Insulated Wide Mouth Bottle Thermos models. This product is a must-have for anyone who owns a Stanley Classic Vacuum Insulated Wide Mouth Bottle Thermos, and is looking for a reliable and durable replacement stopper.