Travel mug/collapsible cup is made of 100% top class food grade silicone, the same material as baby pacifier,BPA free,super soft and flexible and comfortable, collapsible water bottles mouth feel is much better than the cup mouth of stainless steel exposed,because silicone cups mouth is made through two special processes, our travel coffee cup mouth and body are made integrated together, the stainless steel is wrapped in silicone,travel cup is also easy to clean.