Although the founders of S'well, makers of this insulated, stainless steel water bottle didn't actually have breast milk storage in mind when they created this product - it is absolutely perfect for it.   This portable and convenient size easily fits into any purse, pump, or baby bag.  What better way to keep your milk (or any other beverage) cold for 24 hours (or hot for 12) than in a bottle with a chalkboard finish for easy label and date markings?   Ours conveniently comes with a chalk pen that easily wipes off with warm water when names, dates, and other details need to change.  Not looking for breast milk storage?  No worries.  These bottles are great for lunch boxes, mother's morning out snack times, or for the office.