With its lightweight materials and reversible, double-duty design, the CamelBak Arete 18 Hydration Pack 50oz in Charcoal Koi is one of the most versatile packs we make. When you’re not wearing it, it reverses into an insulated reservoir sleeve—perfect for holding your water supply steady inside a larger pack. Ready for a quick hike? Just flip it right side out, and you’ve got room for snacks, layers, essentials, and 1.5 liters of water. Its lightweight materials and packable design also make it an excellent travel bag that won’t add bulk to your luggage. We updated this version of the Arête with additional pockets to keep your gear organized, along with a removable sternum strap.