Willcook, a heater that looks just like a shoulder bag, can turn a cold meal into a piping hot (滚烫的) one in about 20 minutes. The bag is made of a special material called Hotopia that has built-in metal wires, which heat up when electricity is applied. The bag’s inside can reach 80 C in just five minutes. The material looks and feels no different from regular cloth and can also be washed and cut. The bag comes with a battery that can be used for up to eight hours. Users can control the bag’s temperature with a mobile app on their phone.