S'well Vacuum Insulated Stainless Steel Water Bottle, 9 oz, Silver Lining Our bottles feature double-walled construction, designed to keep beverages cold for 24 hours or hot for 12 Our bottles are made from premium grade, BPA-free 18/8 stainless steel. Our 9oz bottle is perfectly sized to keep you hydrated all day long, from your morning commute, to meetings, to yoga class to work. Swell bottles are backed by our one-year Satisfaction Guarantee.