Hydro Flask 18 oz Vacuum Insulated Stainless Steel Water Bottle, Standard Mouth w/Loop Cap, Cobalt Medium (Standard Mouth) opening, Double Wall Vacuum Insulated Keeps Hot up to 6 Hours, Keeps Cold up to 24 Hours BPA-Free, 18/8 Stainless Steel Signature Powder Coat Finish Small enough to transport with ease and ideal for pairing with the Hydro Flask sport cap for one-handed refreshment