In the midst of a long run or hike the last thing you want is to feel bogged down by gear. Hydration, nutrition, cell phone, car keys, tissues, emergency money, etc can all start to feel heavy and bulky if not stored in the right pack. For me, the right pack is the Salomon S-Lab Adv Skin 5 Set. Lightweight and stretchy, the S-Lab Adv Skin 5Set comfortably stores everything I need for hours on end. I barely notice it's on even when fully loaded with fluids. The S-Lab Adv Skin 5Set is available in four different sizes and adjusts easily so you can personalize the fit. The pack has two flasks in front and provides room for a 2-liter bladder on the back. This is allows me to carry Tailwind and plain water at the same time. The pack comes with tons of storage; I can fit all the essentials plus a jacket in the pockets and still have room to spare!