Nathan  TrailMix 12-Liter 2.0 Hydration Vest

First-time buyer for trail running pack, but definitely a little bit of a gear junkie for efficiency. Like the four straps to really dial in your fit on-the-go. Like the expandable pouch on back for a lightweight rain jacket, the pole storage sections great, ample storage for emergency gear. No complaints. At first I couldn't keep the water cord from the bladder retained to the pack (kept falling out), but once I was able to get the pack fitted correctly, no issues.

Fits well, I love the capacity for carrying items. The pockets on the straps are just the right sizes for me. It tightens down well enough that it doesn't bounce while I trot my horse.

Not the best designed pack out there. The pockets in the front are definitely small and awkward while it is comfortable the previous version of this pack was much better.

This is a solid little backpack for trail running, hiking, and cycling with basically everything you need and everything you don't for 3-8 hours outside unsupported. It really has a snug fit, a bounce-free design, and is comfortable, breathable, and secure. It also is very lightweight and a nice shape to be minimally invasive during high intensity workouts, and is attractive enough to not look weird or like you're super tactical or anything. One funny thing they don't really advertise is because it's a roll-top bag, the main pocket actually appears to be waterproof or pretty heavily water resistant. A few things I didn't like as much -- 1. The hydration bladder. The position of this bladder in the bag and where it sits against your back makes it incredibly bouncy. Significantly more so than any other hydration pack I've ever used. I would have appreciated it being wider, and perhaps set a bit lower in the bag so it isn't so extremely noticeable. It's fine, and it works, but jeez, man. It certainly is a bouncing bladder on your back. It also seems like they could have made it significantly larger. Would have loved a better shaped bladder for this bag. 2. The chest straps. It's great that there's two of them, and the strap system is well-intentioned, but because they have so little tension on their "railing", they both just slide together between my chest and stomach. I found myself constantly pushing them back on a long run. This is solvable with a few small pieces of tape to restrict their movement, but it's one of those things that make you wonder why even have a slider adjuster there. Just make them fixed, and it'd probably be cheaper to make and more functional. 3. The size. I can almost certainly say that this is nowhere close to 12L. It's probably more like 8. It does have quite a bit of stretch, so I'm sure you could shove some apparel or soft items in there, but it is best suited for basically putting a change of socks and a light coat in along with some nutrition and a full bladder + some soft bottles in the straps, max. It seems as if it would be better if they just designed it to be a bit wider -- since it's a narrow shape, everything gets forced towards your spine when you pack it full. All said, this is the perfect bag for my use -- 2-4 hours on the bike or on a run, or a solid lightweight pack for a hike where you can pack another layer, some snacks, and a water filter.