Lid has a in-built Steam Ventilator to release Steam while Cooking in Microwave. Kindly open the Clip while cooking in the Microwave. Instruction sheet to make Idlis is provided with the product Made of 100% food-grade virgin plastic, it is unbreakable, dishwasher safe (top rack), Refrigerator Safe & Microwave Cookware. Withstands temperature from -20 degree to + 110 Degrees. Made from new generation polypropylene, this set is free from all hazardous chemical components like BPA, etc.