Made of silicone material. It is dishwasher safe, flexible, and durable. Store it without damage, this boil over stopper is very simple to use, just lay it over your cooking pot. Keep your kitchen counter top, oven, and stove top free of messy boil overs. With a maximum heat resistance up to 230℃,Minimum cold tolerance up to -40 the cover is dishwasher safe for effort free washing.