It’s 13.5oz (400ml), need prepare 2 AAA batteries, put in the mug bottom. Cup made by stainless steel, slide lid with heat emission hole, anti-slip handle. There is a impeller at the bottom which is food grade plastic. Press button to start stirring and press again to stop, without any noise. Free your hands, suitable for family, travel, office, watching TV, business, picnics, etc. For coffee, tea, hot coco, and any other beverage hot or cold. It’s the perfect,unique, stylish and practical gift for family or friends.