Stainless steel outer and inner. Double wall construction for insulation of hot or cold liquids. Snap-on, spill-resistant. Thumb-slide lid with rubber gasket. Due to vacuum insulation technology, capacity is 18 oz. with lid on. Keeps drinks hot or cold up to 6 hours. Non-skid rubber bottom. Meets FDA requirements. BPA Free. Hand wash recommended. Imprinted with the International logo.