This cup leak-proof design, it is recommended into the bag. Another section cup with a warm function (about 2-4 hours), suitable for office ,home ,travel use. Thermal effect : 100°c,after 1hours ,can be kept over 75°c in summer, and over 35°c after 4 hours in winter. 304 stainless steel inner,avoid of unhealthful chemical substances when using under high temperature. Fresh, brief ,healthy are our cups special feature different with other cups.