When I think about the best or most popular backpacks for the lightweight backpacker or thru-hiker crowd, I can rattle off dozens of models from several different brands, no problem. And while I love the brand for its comfortable apparel, Arc’teryx never made that list. So when a coworker at REI whispered in my ear about a lightweight, 45-liter backpack coming from their direction, I was skeptical. Then, after confirming the rumor for myself, I got excited.