Stainless Steel Freezing Cup is made of stainless steel, silicone and plastic. What makes it unique is that it doesn't need to add ice for its cooling function, yet it keeps you cool in the summer. Just fill the hole in the bottom of the cup with water, insert the silicone plug, and put it in the fridge. Take it out and inject it directly to enjoy a cold drink. It has a 330ml capacity and the cup is small and easy to carry.