Made of high-grade 304 18/8 food grade stainless steel, rust and lead free. The advantage is that it is more durable than ordinary cups and can withstand heavy use every season. Stainless steel tumblers are designed with a double layer of vacuum insulation. This means that the tumbler has a very good heat retention effect and can keep your favorite beverage cold or hot for hours. The wide opening fits most ice cubes for easy refills while the smooth, wide-mouth, smooth lip has rounded edges to make on-the-go sipping feel like your favorite mug. With two lids for healthy drinking, quick and easy. Fits most car cup holders, perfect for family gatherings, picnics and barbecues, on the go, in the office, indoors and outdoors, etc.