The subject wants to ask, "Is the thermos cup 306 better or 3 16?" 3 16. Okay. 306 and 3 16 are both made of stainless steel. 306 stainless steel is listed as a "food grade" metal by national standards, and it has no problem in normal contact with water, tea, coffee, milk, oil, salt, sauce and vinegar, while 3 16 stainless steel is further upgraded on the basis of 306 stainless steel, with stronger corrosion resistance.