We had to pinch ourselves while wearing the Primero. Although this pack expands to hold 5,800 cubic inches and comes dressed in bombproof, water-shedding 630-denier Oxford nylon, it weighs only 5 pounds and carries more like a daypack. How? A responsive hip belt working in tandem with a super-light frame gives the pack great flexibility. Forged from aluminum tubing, the internal suspension forms an X shape that rotates in the middle and offers superb bounce. No matter if you’re dodging trees and brush on a cross-country scramble, or just reaching across your body, the bag torques with your torso, allowing for uncommonly natural movement.