With its lightweight materials and reversible double duty design the arecircte 18 is one of the most versatile packs we make when yoursquore not wearing it it reverses into an insulated reservoir sleeve ideal for holding your water supply steady inside a larger pack ready for a quick hike just flip it right side out and yoursquove got room for snacks layers essentials and 15 l of water its lightweight materials and packable design also make it an travel bag that wonrsquot add bulk to yo