Ultimate Direction released updates to all its Signature Series running packs this year with some exciting new changes, including front-side trekking pole holders. I gear tested two of the models, the lower-capacity TO Race Vest 3.0 and the higher capacity AK Mountain Vest 3.0. Fresh off some trail running in the Rockies, here’s my assessment of how they stack up.
TO Race Vest 3.0
Designed by Timothy Olsen, this vest is truly a race vest. It weighs in at 165 grams (5.78 ounces) yet boasts a 5-liter storage capacity.
This makes it both lighter weight and larger capacity (by one liter) than the AK Race Vest 2.0, which I ranked as my favorite low-capacity pack in last year’s review. So I was excited to see how the TO Race Vest 3.0 compared.
Although it has some admirable features—including front-side trekking pole straps—the older AK Race Vest 2.0 model remains by far my favorite low-capacity running pack. Here’s why.
A major disadvantage of the TO Race Vest 3.0, in my mind, are the low-positioned front water bottle pouches. This makes it awkward to carry Ultimate Direction’s 420-mL soft Body Bottles (more on these below) in the front. In fact, I ended up moving both Body Bottles to the rear pockets.
Fortunately, the rear pockets worked well for stowing the two Body Bottles—with a little room to spare for an energy bar or lightweight jacket. But that left me with two unused pouches in the front of the pack. I tried the front pouches with UD’s smaller 10-ounce bottles, but they were difficult to stow/retrieve because they fall to the bottom of the deep pockets.
Aside from my complaint about the awkward positioning of the front water bottle pouches, the TO Race Vest 3.0 is solidly constructed while remaining very lightweight.
I was able to wear it on hot days without a shirt and had no problem with chafing. The upper back is made of a breathable mesh that essentially acts like a skin-tight technical shirt.
The pack comes in three sizes, and adjustable side straps make it customizable to your body. This allows the vest to fit and wear just like a vest rather than feeling like a backpack. Measure around the bottom of your ribs with the clothes you will wear while running to find your size (see the specs below for sizes specific to this pack).
Pros:
- Lightweight, minimalist design
- Mesh upper back stays cool during hot runs
- Can wear without a shirt without chafing
- Straps on the front for trekking poles
Cons:
- Awkward, low positioning of front water bottle pouches
- Not able to use with a hydration bladder
- No bungee cord or hooks on the back for additional storage options
TO Race Vest 3.0 specs:
- Volume Capacity: 305 cubic inches/ 5 liters
- Weight: 5.78 ounces (8.23 ounces with bottles) / 165 grams (235 grams with bottles)
- SM: 24 – 38 inches / 61 – 97 cm
- MD: 31 – 42 inches / 79 – 107 cm
- LG: 36 – 50 inches / 91 – 127 cm
- Price: $109.95
- View on Ultimate Direction website
- Buy on Amazon
Bottom line: If you’re looking for a low-capacity race vest, I would recommend the older AK Race Vest 2.0 over this newer TO Race Vest 3.0.
AK Mountain Vest 3.0
Given how much I liked the fit and functionality of the AK Race Vest 2.0, I was eager to try the expanded capacity AK Mountain Vest 3.0 that promised a similar fit. Despite high expectations, I was not let down with this new model designed by Anton Krupicka.
With the new AK Mountain Vest 3.0, Ultimate Direction finally has a higher capacity running pack that rivals the older Salomon Skin Pro 10 + 3 Set, which I ranked as my favorite larger capacity running pack in last year’s review. In a side-by-side competition, I would have to declare a tie between the two. Each works equally well, and each has its own unique features.
But given that Salomon has replaced the Skin Pro 10 + 3 with the new Skin Pro 10 (a 10-liter pack), the AK Mountain Vest 3.0 boasts a larger capacity at 12 liters (although it is slightly heavier at 330 grams vs. the 278 grams for the new Salomon Skin Pro 10).
What do I love about this pack? Everything.
It fits just as well as its precursor, the AK Race Vest 2.0. Unlike my complaint about the TO Race Vest 3.0, the front water bottle pouches are perfectly positioned so that I could carry two full 420-mL Body Bottles in the front without any awkward bounce.
On the outside of each of the front water bottle pouches are two smaller pockets perfect for stashing a few energy bars, gels or a phone. And the pack is compatible for use with a hydration bladder; you can route the drinking straw over either shoulder.
There is generous room in the rear main compartment for storing clothes, gear or extra food. The two-pronged zipper travels across the top and all the way down one side, allowing for both top and side access. All of the side hip pockets can be zipped shut for secure storage.
Like the other new Signature Series vests, this one also has front straps for quick stowage of trekking poles. Trekking poles? I go with the Black Diamond carbon Z-poles, by far the best poles out there for trail running due to their compact, lightweight design and quick deployment.
Although the front straps work well for storing poles, it’s possible to brush them with your arms while running if you loosen the front chest straps too much. For that reason, I like to have the option to store poles in the back when I don’t need them. Although the AK Mountain Vest 3.0 doesn’t have ready-made trekking pole straps in the back, its versatility allows you to configure your own.
And that’s what I love most about the AK Mountain Vest 3.0—you an customize it to your unique needs. With some extra 3-mm utility cord and cord locks, I created my own straps on the back of the pack using the built-in hooks. This allowed me to secure my trekking poles on the back along with my lightweight CAMP Corsa ice axe.
The AK Mountain Vest 3.0 may be the most versatile and customizable trail running pack out there. It’s lightweight, yet durable enough to carry gear for all kinds of mountain running adventures.
Like the other Signature Series vests, the AK Mountain Vest 3.0 comes in three sizes and contains adjustable side straps so you can dial in the fit. Measure around the bottom of your ribs with the clothes you will wear while running to find your size (see the specs below for sizes specific to this pack).

Pros:
- Solid, lightweight construction with great storage capacity
- Well-positioned front water bottle pouches eliminate bounce
- Can wear without a shirt without chafing
- Straps on the front for trekking poles
- Plentiful accessible storage pockets
- All pockets have zippers for secure storage
- Bungee cord on back for stowing a jacket
- Extra hooks on back make it easily customizable
- Hydration bladder compatible
Cons:
- None
AK Mountain Vest 3.0 specs:
- Volume Capacity: 702 cubic inches / 11.5 liters
- Weight: 11.55 ounces (14 ounces with bottles) / 330 grams (400 grams with bottles)
- Price: $149.95
- SM: 24 – 33 in. / 61 – 84 cm
- MD: 31 – 40 in. / 79 – 102 cm
- LG: 36 – 46 in. / 91 – 117 cm
- View on Ultimate Direction website
- Buy on Amazon
Bottom line: The best 12-liter running pack for anything from basic trail running to more ambitious mountain running adventures. Its fit and customizability are hard to beat.
Body Bottle
Although I understand and appreciate the concept of a soft water bottle, I gave an ambivalent review last year of Salomon’s soft flasks. This year, Ultimate Direction has come out with their own version of the soft flask—the Body Bottle. Two 420-mL Body Bottles come with both of the packs reviewed above.
I can report that Ultimate Direction nailed their version of the soft water bottle. The Body Bottle, from my perspective, represents a substantial improvement over Salomon’s soft flasks for two reasons. First, the bottle itself is wider and therefore has more structure when holding it in your hand. Second, the mouth of the bottle is wider, making it easier to fill and, if desired, add an electrolyte mix.
In addition, these bottles fit perfectly within the water bottle pouches of the Signature Series vests. With the AK Mountain Vest 3.0, I was able to drink directly from the Body Bottle without even removing it from the pouch. This made for convenient hydration while running across dicey terrain. Plus, the bottle fit nicely in my hand, allowing me to simply carry it when desired.
Of course, the wider mouth ensures that the Body Bottle is not compatible with the Sawyer Mini water filter I use on the trail. For that, I still carry a Platypus bottle. But it’s nice to have a Body Bottle along when you’re able to fill up at potable water sources.
Body Bottle specs:
- Weight: 1.08 ounces / 30 grams
- Fluid Capacity: 14.2 ounces / 420 mL
- Material: BPA-Free TPU
- View on Ultimate Direction website
- Buy on Amazon
Disclosure statement: The products tested for these reviews were purchased from Ultimate Direction at a discount.