Arc'Teryx Men's Cierzo 18 Backpack, Inkwell, One Size CIERZO 18 BACKPACK - Summit packs are special breed. They are required to comfortably carry their contents, but do it for minimal weight. The materials need to be tough enough for alpine environments, but packable enough to fit in a minimalists backpack. ALPINISM & CLIMBING - Climbing equipment designed for efficient movement and protection in alpine environments