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Seek Outside Unaweep 3900 Backpack Review

Off-Trail with the Seek Outside Packs Unaweep Backpack
Off-Trail with the Seek Outside Unaweep 3900 Backpack

One of the areas of the ultralight backpacking market that has long been underserved are lightweight (3-4 pound) durable backpacks for heavy loads exceeding 40 pounds and ranging up to 60, 70, or 80 pounds or more. Built using modern lightweight yet durable fabrics, with more streamlined UL-style designs, such packs would be ideal for backpackers, climbers, and guides wanting to take longer trips into less developed wilderness areas with limited resupply options.

There’s actually a growing audience for packs of this type, particularly among backpackers who’ve been schooled in ultralight backpacking techniques but are ready to move onto expedition-style adventures that require carrying additional gear such as packrafts, bear canisters, climbing gear, and even hunting equipment. While some attempts have been made by UL pack manufacturers to address this market by developing higher capacity packs with high-tech materials, those attempts have largely failed because they have shied away from adding more robust frames to their packs. Heavy loads require a frame. Period.

Paradox Packs Unaweep 3900 is basically an external frame with an internal frame pack bag sewn onto it
Seek Outside Unaweep 3900 is basically an external frame with an internal frame pack bag attached to it

It’s not surprising then that Seek Outside, a gear manufacturer with roots in the hunting community is beginning to develop a following among lightweight backpackers who need to carry much heavier loads in the 40-80 pound range and higher. Seek Outside has succeeded in combining a streamlined pack bag made out of bomb-proof high-tech fabric (X-Pac) with an adjustable external frame suspension system capable of carrying heavy loads comfortably with their Unaweep line of backpacks.

I’ve been testing one of Seek Outside’s packs, a Unaweep 3900 for the past two months, and I’m very impressed with its lightweight (just over 3 pounds), durability in brutal off-trail conditions, and comfort when carrying 40-55 pound loads. With a few tweaks, this hunting-inspired pack has the potential to satisfy the needs of a broad segment of backpackers and guides who need to carry more gear and supplies but aren’t willing to carry an overbuilt  8-9 pound backpack to get the job done.

I doubly excited because Seek Outside is making changes to the Unaweep design to make it more palatable to a backpacking audience and open to suggestions about how to modify the Unaweep design to address a non-hunting audience’s needs. I have been looking for a multi-day off-trail backpack that has many of the properties of the Unaweep 3900 for a long time and I think that Seek Outside has a good shot at satisfying my needs with a few minor modifications.

The Talon (black) is an external pocket that attaches to the pack bag using compression straps.
The Talon (black) is an external pocket that attaches to the pack bag using compression straps.

Storage and Organization

For purposes of description, the Unaweep has three separate but integrated components: the frame (including shoulder straps and hip belt), a pack bag which is permanently attached to the frame, and an external pocket, called a Talon, which attached to the main pack bag using compression straps.

The red pack bag (above) is nothing fancy. It’s a big sack with a roll-top closure. The seams aren’t sealed with seam tape (so it’s not waterproof) and there isn’t an internal hydration pocket or hydration ports. The only functional elements on the pack bag are two water bottle pockets with bottom drainage ports. The water bottle pockets have cord-locks around the top rim that provide some compression to hold bottles in place, but that’s it. The hip belt and compression straps are attached to the frame but not the pack bag, unlike many internal frame or ultralight backpacks.

The roll-top closure provides vertical compression on the contents of the pack bag but the ends of the roll-top connect to one another instead of being tucked away along the sides of the pack bag. This caused me some concern because I bushwhack a lot and feared that the resulting loop would catch on vegetation but that has never occurred. The top of the pack bag is further secured with an external Y strap that runs over the top of the pack bag and can also be used to attach gear to the outside of the pack.

The Unaweep's side water bottle pockets are not tall enough. When carrying two 1 liter bottles, thebottles tend to pop out of the pockets and full reservoirs flop over the pocket sidewalls, with no way to secure them to the side of the pack..
The Unaweep’s side water bottle pockets are not tall enough. When carrying two 1 liter bottles, the bottles tend to pop out of the pockets and full reservoirs flop over the pocket side walls, with no way to secure them to the side of the pack (as shown above). This is because the bottom compression strap runs flush against the top of the pocket and is not positioned higher up the pack’s sides.

Despite being an external frame pack, you pack the Unaweep the same way you would any internal frame pack, with the heaviest items as close to your back and core muscles as possible. That means you’d probably put your sleeping bag in first on the bottom, followed by your sleepwear, then your longer-term food (heavy), and so on like you’d normally pack an internal frame backpack. You want to avoid packing very heavy items toward the top of the pack because the external frame noticeably increases the efficiency of rotation when you lose your balance. I made this mistake on an off-trail hike with a heavy pack and did a few face plants before I reorganized the distribution of weight in my backpack.

Every Unaweep 3900 comes with a Talon pocket that attaches to the pack with eight compression straps, three on each side and two at the bottom. The Base Talon (1000 ci/ 16.4 L ) has a side zipper running down its length and provides short-term storage for items that you want during the day so you don’t have to open the roll-top pack bag. I carry my water filter, Aqua Mira, and day time snacks in mine, along with a full three-liter hydration reservoir when I need to carry extra water to a dry camp. Unfortunately, the Talon doesn’t have drain holes to help drain a wet filter, but then again the water doesn’t have a chance to soak into the main pack bag because the Talon is its own separate compartment.

Carrying a wet tent on the back shelf of the Seek Outside Unaweep Backpack
Carrying a wet tent on the load shelf of the Seek Outside Unaweep Backpack

As you can imagine, the Talon also provides an excellent way to attach gear to the outside of your backpack, such as snowshoes, if you sandwich them between the Talon and the pack body. There’s a built-in load shelf permanently attached to the bottom of the frame to facilitate this type of carriage, really just a piece of fabric attached to the bottom of the pack frame and on the other end to the Talon by webbing straps. You can even stack up gear horizontally, like a tent or a z-lite pad, and so on.

If you decide you want to discard the Talon, the load shelf and it’s two webbing straps will flap annoyingly below the frame. While you could simply cut the load shelf off (an irreversible modification), you can preserve its functionality by connecting the webbing straps to the middle tier of side compression straps on the pack body. It’s a sloppy solution though because it creates two long pieces of webbing on the exterior of the pack that are easy to catch on passing vegetation. Hiking without a Talon also eliminates any easily accessible external storage on the Unaweep, forcing you to stop and open the packbag to access and stow gear or food, something I would find undesirable because of its negative impact on transition times.

Interior of Base Talon Pocket
Interior of Base Talon Pocket

The Unaweep 3900 pack bag is available in a number of different fabrics and there are different function-specific Talons that you can choose depending on your needs. The red pack shown here is made with a 70 denier (a measure of thickness) waterproof fabric called VX07 X-Pac and the black fabric on the Talon is a 420 denier fabric called VX42. Originally developed for sailcloth, X-Pac fabric is tear-resistant,  waterproof, and has a multi-layer construction which gives it a very good structural stability. It can also be sewn.

While I haven’t experienced any durability issues with the VX07 on the red pack, Seek Outside has since switched to making the Unaweep 3900 out of even more durable grades of VX21, and VX42 because they add substantially more durability against rock and talus abrasion. Seek Outside also offers other grades of X-Pac including VX07 and VX33, in addition to less durable but lighter weight Dyneema Fiber, although this adds to the time required to sew a custom pack.

If you are interested in buying a pack from Seek Outside, I recommend you call them to place your order rather than making a selection on their website, if only to make sure you understand what you are buying and its weight/performance tradeoffs. The company is also a cottage manufacturer that makes gear to order, so you really need to do your homework to make sure you’re ordering what you want.

Unaweep External Aluminum Frame
Unaweep External Aluminum Frame

Backpack Frame and Suspension System

The Unaweep 3900 is an adjustable external frame backpack made out of 6061 aluminum tubing which is curved to hug your back, making it more like an internal frame pack than a mainstream external frame pack like the Kelty Trekker or an Alps Mountaineering Bryce external frame pack where the frame extends beyond the bottom of the pack bag. There’s minimal padding on the frame at mid-back level to promote airflow so your sweat can dry, but this is marginally effective in hot weather because the pack rides so close to the back of your body.

The length of the torso is adjustable using a very simple webbing system that raises or lowers the height of the shoulder yoke using webbing straps attached to the piece of fabric that spans the frame at mid-back. It’s also very easy to adjust while wearing the backpack: simply shoulder the pack, tighten the hip belt, then adjust two ladderlocks on the frame (inside the load lifter straps) to allow the shoulder harness to rise to the point where the top of the harness is near C7 – the pointy vertebrae at the top of your back. (click for video instructions). This enables the Unaweep to be adjusted for torso lengths ranging from 15.5″ to 22″ (frame extenders are also available for longer torsos).

The remainder of the shoulder strap system is quite simple with moderately padded shoulders straps and load lifters attached to the top of the frame. The sternum strap does not have a whistle and outside of the straps are devoid of any daisy chains or external attachment points for hanging a camera or GPS pocket.

The hip belt is bolted to the bottom of the frame using grommets and lock nuts.
The hip belt is bolted to the bottom of the frame using grommets and lock nuts.

The hip belt is literally bolted to the frame using locking nuts that attach along the frame the bottom near the sidebars. While crude looking, the Unaweep hip belt provides an amazingly efficient load to hip transfer, something everyone who tries on this pack comments on immediately. The effectiveness of the suspension under load is due to the fact that the hip belt is attached to the frame directly, a principle that is well understood by pack makers, but not often used in packs developed to carry lighter loads where a real frame is unnecessary.

Comparable External Frame Backpacking Packs

Make / ModelVolume (L)Weight
Mystery Ranch Terraframe50L, 80L5 lbs
Seek Outside Gila57L2 lbs 10 oz
Seek Outside Divide74L2 lbs 12 oz
Seek Outside
Unaweep 4800
79L2 lbs 11 oz
Vargo ExoTi AR246L2 lbs 12 oz
Vargo ExoTi 50L2 lbs 11 oz
ZPacks Haul Ultra60L1 lb 3.6 oz

The hip belt is 6 inches wide increasing the surface area over which weight can be distributed and helps prevent the belt from sliding down, particularly for men who have squarish hips where this is a problem. It also uses a Scherer-style cinch with pull forward webbing that provides a mechanical advantage when tightening the hip belt (I recently became friends with the designer who invented this feature when he worked for Kelty, Michael Cecot-Scherer at

The current Unaweep lacks good attachment points on the shoulder straps. I was able to rig up a map holder, cammera pocket, and tracking device/PLB attachment using spare parts but it's be far cleaner daisy chains or other attachment points were provided with the base backpack.
The current Unaweep lacks good attachment points on the shoulder straps. I was able to rig up a map holder, camera pocket, and a tracking device/PLB attachment using spare parts I had in my gear repair drawer but it’d be far cleaner if daisy chains or other attachment points were provided with the existing shoulder harness.

Areas for Improvement

I really like the Seek Outside Unaweep 3900 and I’ve seriously considered buying one for my personal use. The load to hip transfer provided by the external frame is phenomenal and the tubular frame leads to much better postural alignment and hiking efficiency in rugged conditions. While Seek Outside has moved away from offering the VX07 fabric used in this loaner pack, I’ve found it to be extremely durable for off-trail bushwhacking in dense spruce that tends to slice through the fabric and mesh of UL backpacks like butter. Coupled with its lightweight (just over 3 pounds), these attributes make the Unaweep a very appealing backpack for my needs.

The Unaweep 3900 has a body hugging shape and three tiers of compression straps that help bring the load closer to your strongest core muscles.
The Unaweep 3900 has a body-hugging shape and three tiers of compression straps that help bring the load closer to your strongest core muscles.

But the fact remains that the Unaweep and Seek Outside’s other packs were originally designed for hunters and not off-trail backpackers. If you decide to take the plunge with the current Unaweep model there, are a few details that you want to know about the pack (none of which are showstoppers – but can be annoying), including modifications that Seek Outside plans to make to the pack that is designed with backpackers’ needs in mind.

  1. Seek Outside plans to offer a version of the Unaweep without an external Talon pocket, replacing it with a front pocket sewn into the pack body. UL backpackers who prefer having a pocket like this will appreciate this option.
  2. The shoulder straps on the Unaweep don’t have extra attachment points for hanging gear such as map cases, cameras or GPS units. Seek Outside will sew extra daisy chains onto the shoulder straps as a customization or you can add your own attachments points using tri-glides.
  3. The hip belt webbing buckles have a tendency to fall off the webbing because the ends aren’t folded over and sewn together. Many of Seek Outside’s packs are made to order – so be sure to request this or do it yourself. Losing a hip-belt buckle in dense woods would be disastrous.
  4. The side water bottle pockets aren’t big enough to fit two, one-liter soda bottles side-by-side and should be made taller so the bottles don’t pop out so easily.
  5. The bottom compression strap should also be raised slightly higher above the water pocket so it can be used to secure tall objects in the side water bottle pockets to the sides of the pack bag.
  6. The hip belt and shoulder straps are lined with black spacer mesh with picks up spruce needles and duff on off-trail hikes.


  • Exceptional load to hip transfer. Carries wonderfully with higher weights of 40 pounds and up.
  • Easy to adjust torso length system
  • Durable fabric and solid water bottle pockets (not mesh)
  • No torso collapse with heavy loads
  • The wide hip belt is comfortable and doesn’t slip under load


  • Slow transition times because you need to unbuckle Y strap and roll-top to access gear
  • Water bottle pockets are too low, so bottles pop out of them. Cordlock system is awkward to use while wearing the pack.
  • difficult to fit two 1 liter bottle in water bottle pockets
  • Lack of attachment points on shoulder straps

Manufacturer Specs

  • Weight of reviewed pack: VX07 with base Talon: 3 lbs 3.7 ounces, without Base Talon 2 lbs 14 ounces
  • Fabric choices:
    • VX21 with Base Talon 3 lbs 2 ounces, without Base Talon 2 lbs 12 ounces
    • X33 weights are comparable
    • Cuben 2.92 saves 8 ounces with pack bag and talon  (2lbs 10 ounces)
    • VX42 adds 4 ounces complete
  • The adjustable frame fits torsos sized 15.5″ to 22″. Frame extenders are available for people with even longer torsos.
  • Hip belt sizes
    • Small: 29-32″ waist
    • Medium: 32-36″ waist
    • Large: 36-40″ waist
  • Pack bag volume: 3900 cubic inches, roll-top closure
  • Talons: Multiple options available (see website). Base Talon has a volume of  1000 cubic inches.
  • Standard features:
    • Pack bag roll-top closure
    • Two side water bottle pockets
    • Three tiers of side compression straps
    • Base Talon with integrated load shelf
    • Easy to adjust torso length
    • Load lifter straps
    • Sternum strap
    • Dual ice axe loops
    • Webbing loops on hip belt
    • White pack interior for better visibility
  • Customization options:
    • Side access zipper on main pack bag
    • Hydration ports
    • Call for other requests
  • Bear canister compatibility
    • Garcia Bear Canister
    • Bear Vault BV500
  • Compatibility
    • compatible with pocketed lid (purchased separately)
    • compatible with Gun Hook (purchased separately)

Disclosure: Seek Outside loaned Philip Werner ( a Unaweep 3900 backpack for this review. 

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  1. Interesting pack. Seems to share some characteristics with the ULA Epic which I can relate to – the inadequate side pockets (even worse on the Epic as they also swing about), the load shelf etc.

  2. Nice review. I picked up an unaweep this summer. Minor quibbles aside as someone who does have squarish hips this is the most comfortable pack I have ever used, period. I have about 140 miles of backpacking on it and I just can’t get over the comfort. I’ve used traditional internal frame packs from osprey, ula, and granite gear and there is no comparison on the hipbelt comfort. No slipping, no pressure points, and it just nicely distributes weight all thru the hip belt instead of focusing it in the lumbar area where the stays or frame sheet terminate. I like the talon, it provides huge flexibility in how you strap things on and will easily compress even day pack loads. One thing you didn’t mention is that besides adjusting the harness you can adjust the frame height. I have a longer torso so run the pack with 4 inch extensions instead of the standard 2 inch. I get excellent load lifter action something lacking in many packs

    • I’d mention the frame extenders in the specs, but made an edit to call them out in the text.

      Did you get the 3900 or the 4800, and which fabric/color did you choose? I’m also thinking about getting a Uniweep for winter but cant decide on the volume. Fantastic bushwhacking pack – I’ve easily put 100 miles on it during testing.

      • I have the 4800 with the grey vx21. When I ordered they were still putting the side zip on the pack by default. I don’t mind the extra volume. It compresses well enough it is not an issue and useful for winter then. I liked it so much I’m selling my other two backpacking packs and ordered a 2nd unaweep for a spare. I’m getting a vx-42 with no side zip and slightly longer shoulder harness as I did think the stock harness I got could be a little longer. I forgot to say I was impressed with the vx-21 fabric when I was hiking in an all day rain. It did not absorb an exsessive about of water, must less than say my old osprey pack, dried fast afterwards, and despite the zipper and unsealed seams everything inside stayed dry, although I still did have sleeping bag/clothing in a trash compactor bag.

        • You read my mind. :-) I’m thinking about swapping in a Unaweep for my winter pack and have been flip-flopping on the issue of volume. Looks lik ethe 4800 is the way to go. I can’t get a WM Puma (-25) in through the top of the 3900.

          What do you think about getting the 4800 in cuben. A sub 3 pound winter pack is awful tempting, or stick with the X-Pac?

        • I thought about getting my 2nd in cuben, but I decided I wanted super durability of vx-42, the weight penalty is not that great. Has to be at most half a pound and I’ve been impressed with the xpac fabric, this was my first time seeing it.

        • I ordered the Unaweep 4800 in cuben fiber with the 4 inch extenders. I was debating on the Base talon or not, but two weeks after I ordered the pack, decided to order the base talon afterall. I’m still waiting on the pack to be made. One of the drawbacks with ordering from a cottage company is the time it takes to custom produce a pack, but the customer service when answering my questions via email promptly on a Sunday night was phenomenal. I’m glad you liked your pack, I was torn between an Unaweep or a Z-paks Arc blaster, but the ability to carry more than 30 pounds comfortably is what swayed me. Hopefully the cuben fiber lasts, and if it doesn’t, I can always order a replacement packbag.

  3. A very thorough review on a pack that has intrigued me for a while. I have not used an external frame pack since … But as you say with new materials etc. they become an option for big loads and may even be better for big loads, I am not sure on that point.
    I like the design of the pack and would love to try one, especially a non hunting version. I look forward to hearing about your experiences should you proceed with a cuben version.

    • I find that for non big loads I prefer this pack. Even at a weekend load of low 20s in pounds I find it more comfortable and easier to use than say my GG Crown that I had been using for lighter loads. At least for me I have finally found the pack I can use for anything from a lightweight summer weekend, to a winter trip, to a 7 day long hike, and hauling a bunch of stuff if my wife it along.

  4. I own the Unaweep 4800 and I am completely in love. Hands down the most comfortable pack I have ever worn and the simplicity of the system has grown on me. I arrange my stuff sacks of gear horizontally so that their opening faces the side zipper for quick access without having to access the roll top. And the Talon compression makes it ridiculously easy to setup the pack for any size load. I recommend to anyone on the fence that you go with the larger size (4800) and keep the Talon. With a roll top and the Talon you can “shrink” the 4800 super easy but then you still have a damn big pack if you ever need the full volume. I agree the water bottle pockets are not perfect and small design changes would be welcomed. Having used this pack on backpacking trips and hunting/backpacking trips I give the pack a 95/100 overall score.

  5. Nice job Phillip, I’m glad it worked out for you.

    VX07 does very well in brush, I assume because the laminate construction makes it so slick; branches just slide right off. It does less well when abraded against rock, or against things like snowshoe crampons or skis when they’re carried on the pack. Personally I’m a big fan of VX42, a massive upgrade in durability in all respects without being too heavy.

  6. Am I the only one frustrated with trying to buy a larger ULTRA light backpack? We don’t need it for the weight. That’s why we’re ULTRA light backpackers. But even with the ul tent, stove, bag, pad, etc, for a 6 day trip, we need a pack with more VOLUME! It is nearly impossible to find an 80L pack that is truly UL. Heck, we don’t need a beefy frame for 60# (!!!); we just need more S.P.A.C.E. Grrrrr!

  7. Nice thorough review!
    Does this pack is quiet?

  8. Hi Phil, I’m surprised nobody mentioned anything, but it appears that there are NO hipbelt pockets. It is hard to tell in the pics. Anyway looks like a nice pack.

  9. Thanks Phillip. It is pretty clear in detail. I have no hesitation now for my hiking backpack.

  10. Hey there!

    A bit late now but I think you should update the capacity for the Seek outside packs. The capacity you have listed is just for the internal compartment only. But when you add the side pockets and mesh front pocket you add easily another 15L+. The Specs are as follows:
    Gila: Front pocket 9.8L Side pockets 4L Total= 70L
    Divide: Front Pocket 13L Side Pockets 4L Total= 91L

    You include zpacks and other notable companys full capacity specs (inclusive of exterior pockets).

    Example: Arc haul is actually only 49L internal and then exterior pockets bring it to 62L

    Quite important, as a 15L+ fluctuation in size can really determine whether or not someone justifies the weight, cost, dynamics of the pack when looking at these all objectively…

    • I used the industry standard, which is to only count closed storage in a backpack volume calculation. I can’t help it if Zpacks and other cottage manufacturers try to inflate their specs, so people think they’re getting more volume than they’re paying for (or they’re just clueless and don’t know about it, which is more often the case than not).

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