The 12 oz size Hydro Flask is perfect for those looking for a smaller size that can easily fit into a handbag, purse or small backpack. The Standard Mouth bottle features a larger mouth opening and is ideal for coffees, teas, mixing sport drinks, or just for those who need to take in more hydration at a quicker pace. As with all our bottles, they fit perfectly in most car, bicycle, and stroller cup holders and water bottle cages. Our water bottles were developed to perform in every environment. Each Hydro Flask is cast from double wall vacuum insulated food grade 18/8 stainless steel, therefore they are BPA-Free and resistant to bacteria and odors. The double wall vacuum insulation technology allows Hydro Flasks to keep contents hot for 12 hours and cold for 24 hours.