What Our Gearhead(R) Experts Are Saying:"This pack's internal frame adds stability without extra weight, and I appreciate the easy-access roll-top for quick adjustments. The harness system is incredibly comfortable, even with a heavy load, and the durable, weatherproof fabric stands up to the elements."For those of us who crave the flexibility to explore without limits, the Peak Design 45L Outdoor Backpack delivers. This internally framed pack combines durability with versatility, giving us the room we need for gear-heavy adventures while maintaining a sleek and balanced carry. The Ultra Cinch roll-top design expands an additional 10. 5 liters, providing extra space when we need it, and the lightweight Terra Shell fabric is tough enough to weather any challenge. With smart internal and external organization, from hydration sleeves to multiple external pockets, this pack helps us stay prepared for any unexpected turns on the trail.