Raisenne is made of food-safe Polyethylene Terephthalate (PET) plastic. PET is a clear, strong and lightweight plastic that’s used widely for packaging beverages and food, including soft drinks and water. PET does not contain any Bisphenal-A (BPA). Although PET is a food-safe material, Raisenne was designed for raising dough in a bowl or other container and not for warming food placed directly on the warming surface.