Pack Access and Organization
It’s a big pack, but your gear doesn’t get lost in the hull. The Altra 75 has a large top access opening allowing for easy access to the main compartment, and the inverted U shaped full-length zipper provides full panel loading access, which makes packing and unpacking easier. There are three pockets in the lid providing plenty of space and organizational options.

Smart details
What makes this pack stand out are the smart details most packs overlook. For example, the two top lid pockets are seam-taped, so they are waterproof, and have zippers on the top of the lid instead of on the side like most packs – more like a suitcase than a backpack — that makes for easy access.

Another example: the offset bladder sleeve. The Altra 75 comes with an internal zippered hydration pocket on the side of the backpack and not in the middle, like other backpacks.  This allows for extra room in the main compartment.

Pockets
No problems here: A side-stretch mesh stash pocket on each side of the pack easily holds a 1-liter water bottle and 2 stretch mesh stash pockets on the hip belt are great for storing a snack, small camera, or bandana.

Hip Belt
On this pack, Arcteryx’s AC2 suspension dynamic suspension felt more like a marketing ploy than a real performance enhancement. In theory, the system allows the hip-belt to move with your hips and allows for more comfort. While the hip belt was indeed comfortable due to its thick padding and wrap-around feel, I found no noticeable difference between the Arcteryx pivoting hip belt and a more traditional non-pivoting hip belt. I also found that the hip belt straps would slip at times while hiking. This did not occur regularly, but just enough to be annoying.

Backpanel
The back panel and shoulder straps are comfortable and allow for good air movement, though not the best among packs in this category.

Stability
Heavy loads? Check. The Altra 75 was stable and performed well carrying loads in the 50 pound range. The pack did not shift on steep ascents or descents and it felt secure even during the occasional scramble. Although my pack did not exceed 52 pounds on any trek, I would have no hesitation in increasing the weight and would expect the same stability on loads up to 60 pounds.

Overall Comfort
For adjusting between different users, the Altra 75 lets users select from one of a few pre-determined sizing options. The system is a bit clunky and doesn’t accommodate a perfect fit if you’re between those options. I eventually settled for a “sufficient” fit rather than a really comfortable one. The thick padding on the hip belt and shoulder straps and the easy adjustment mechanism on the load lifters and hip straps, came in handy whether on easy terrain or while ascending or descending on steep grades with heavy loads, both of which somewhat offset the effects of the size-adjustment system.