Comfort/Fit
The Deuter ACT Zero 50+15 received a low score due to the pack rubbing one of our testers creating bruises on pressure points from the lumbar system used on the pack while others found it a comfortable hiking pack with weekend or smaller sized loads. The VariQuick suspension system allows for quick and easy trailside adjustments of torso length, perhaps the easiest of all the packs we tested. This one feature makes this back perfect for kids and teens that are still growing; this pack can easily grow with them. It also allows for the pleasant prospect of hand-me-down bags, since it can be ready in 60 seconds or so for a new user. The vertical bars of padding are comfortable for a number of body shapes, though, clearly not all. 

Storage
The Deuter ACT Zero packs enough for a weekend length trip but may be too small for bigger users and longer trips. Most testers would have preferred more room in the main storage area instead of an outside pocket that didn’t have much versatility. We did get two bear cans in the ACT Zero, but it was a stretch. This pack expands out and cinches in well, and can handle just the camera and lunch just as easily as it can handle a weekend length trip. Trips longer than three days seem to stretch the range of this bag, even when base weight is pared down to a minimum. 

Stability
On a macro level, the torso length is easy to adjust and carries comfortably for most body types in mild to moderate terrain. On a more precise level, testers appreciated how easy it is to make micro-adjustments to account for different conditions and loads throughout the day. There isn’t much much swivel in the ACT Zero, which isn’t helped by the short and squat interior compartment. When this pack gets over packed there’s nowhere to go but up, which can lead to some very top heavy loads. The bag’s center of gravity can change rapidly with just a few gear shifts. 

Durability
Our tester appreciated the durable aluminum hook-and-clasp style closures on the ACT Zero. They are more durable, lighter, and this instills confidence in the bag. The waist and sternum straps are plastic, but they don’t appear as flimsy as other buckles in the test set. The fabric of the water bottle sleeve is also a bit more beefy than some of the other bags. When you consider the overall construction of the bag, it seems surprising that Deuter got away with packing all that durability into only a 511 ounce backpack. The external fabric chosen for the bag stays clean and seems durable. The metal hooks and hard plastic buckles hold under duress. Zippers are beefy but smooth. 

Extras
The ACT Zero has one hip pocket, which is plenty. It also has a narrow brain, which will fit the essentials but not War and Peace. There is one gear loop that could handle an ice tool and two smaller elastic ties for trekking poles. One thing that we appreciate about this bag are the lower tie-downs, which instead of being on the bottom (and being unable to stand up when a tent is lashed down there), they are on the very bottom of the back, which enables a tent to become more of a kickstand to keep the bag standing straight up. A row of neat, standing backpacks on the side of the trail is a much better sight while you eat lunch than a pile of bags heaped atop each other.