These silicone bowl liners are custom molded to fit KitchenAid 4.5 to 5 quart tilt-head stand mixer bowls. Each liner drops in snugly to protect your stainless steel bowl from scratches and reduce mixing noise. When mixing is done, lift the liner out and snap on the airtight lid, which has a sliding timer pointer and a fermentation vent for storing or proofing dough in the refrigerator. Built-in measurement markings let you measure as you mix. The liners are made from thickened, BPA-free, food-grade silicone that handles temperatures from minus 40 to 464 degrees Fahrenheit. They are freezer, refrigerator, and microwave safe, fold flat for storage, and can be washed by hand or in the dishwasher. The set includes three color-coded liners in red, black, and gray with three matching lids to keep ingredients separate. This product is not manufactured or endorsed by KitchenAid.