Hydro Flask’s insulated water bottles are made of high quality food grade 18/8 stainless steel. Marked down from $44.99 to $24.05 with code PZY5 at checkout. Free Shipping when you spend $25. The bottles have no liner (like most aluminum bottles) and are BPA free. Unlike plastic water bottles or single wall stainless bottles, Hydro Flask will keep your beverage of choice at your preferred temperature for hours, whether you choose hot, cold or room temperature liquids.