CamelBak makes the best of the best, but if you’re not certain exactly what these are, let’s break it down a bit, and tell you one of the most common and effective forms of use. Hydration packs are insulated containers on your back, taking the place of your backpack or fitting beside/over them, giving you access to a tubed mouthguard. That has a bite grip (usually) that releases water from the reservoir on your back, keeping you hydrated out on your hike.\r