This 18 1/2 quart Paderno World Cuisine aluminum couscoussier steams couscous. Moroccan Couscous, a semolina-based or ground wheat dish, has its own two-tiered vessel; the couscoussier. The bottom stew pot holds meats and vegetables, providing flavorful steam to the upper couscous filled bottom perforated pot. This 3-piece set is made of aluminum.