Sometimes I want to carry a small amount of water and a full size canteen, Nalgene bottle or Camelbak is too much. This 1 pint pilot's flask is perfect. It's small and low-profile. It's about 6.5" x 4" x 1.75". I've carried it in an inside chest pocket with my backpack straps over it and I barely noticed it at all. I got this one on eBay for about $5 shipped.