These reusable wraps are made from food-grade silicone, and are dishwasher, microwave, fridge and freezer safe. FDA and LFGB approved silicone. They are stretchable, so can fit any shape of bowl, and form a tight seal. Will form a seal on any smooth surface.Working temperature range of -40C to 230C.After each use, clean lids with soap and hot water or put in the top shelf of the dishwasher. Avoid abrasive cleaners.Each pack contains 6 sizes:21cm, 16.5cm, 14.5cm, 11.5cm, 9.5cm and 6.5cm diameterReusable cotton mesh bag included.