View Larger Product Description The Narrow Mouth bottle is our original mouth size. The mouth has a width of 1.44 in / 3.7 cm. The Narrow Mouth Hydro Flask is ideal for keeping your liquids chilled all day or warm well into the evening. Ice cubes from standard refrigerator ice dispensers fit perfectly through the Narrow Mouth. Our water bottles were developed to perform in every environment. Each Hydro Flask is hand cast from double wall vacuum insulated food grade 18/8 stainless steel, therefore they are BPA-Free and resistant to bacteria and odors. Our double wall vacuum insulation technology allows Hydro Flasks to keep contents hot for 12 hours and cold for 24 hours. What's Inside the Hydro Flask Vacuum Insulation The entire Hydro Flask line is vacuum insulated which means there is an absences of matter between the two stainless steel walls. Since there is no matter, the temperature outside of the flask has a difficult time affecting the temperature inside the contents of the flask. Cold Up to 24 Hours / Hot Up to 12 Hours Due to the fact that our flasks are vaccuum insulated, your hot beverages stay hot up to 12 hours and your cold beverages stay cold up to 24 hours. 18/8 Stainless Steel All of our flasks are made of 18/8 stainless steel; BPA free and highly resistant to absorbing odor, taste, and bacteria. They are simple to clean, don't have a liner to scratch, and are completely recyclable. Powder Coating Hydro Flasks come in a multitude of color choices with a powder coat finish, as well as the classic stainless. Sweat Free Our double wall vacuum insulation prevents condensation with your cold drinks. And when you are drinking a hot beverage, the vacuum flask prevents the heat from transferring to the outside of the Hydro Flask, so your hands should always be comfortable.