Fortress Lightweight Waterproof Backpack Color Alpine Gray

Unaweep 3900 Backpack

$389.00 389
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  • Product Description

    Lean and trim the 3900 carries close to the back, and is an ideal choice for outdoorists who generally carry lower volume loads, but still need serious load hauling capability as well as the overflow and odd load taming ability of the Talon system.  Early season hunters, expedition canyoneers, backcountry skiers, and taller backpackers will all do well with the Unaweep 3900, the specialists tool.

    Handmade in Grand Junction, Colorado, USA.



    • Revolution articulating frame.  Body-hugging, dynamic under light loads, and rigid under heavy ones.  Our suspension will carry anything you can lift, all without feeling like a backboard.
    • X-Pac packbag material - forever waterproof, better tear and abrasion resistance than traditional pack fabrics
    • Dual side bottle pockets with shock cord closure; loosen, access and recinch with one hand on the go.  Shock cord is user replaceable for long service life.
    • Dual ice axe loops
    • Three horizontal compression straps
    • One over-the-top "V" compression strap
    • Two lower load shelf compression straps
    • Infinite adjust harness custom fits any torso length



    • Adjustable frame, Can be used at 24"-  28" height. Optimized for 26 inch height.  
    • Four hip belt sizes, fits 29 to 42 inch waists



    • Constant 36" diameter
    • 37" unrolled height
    • 35" max height when closed


    Weight (includes Base Talon and all compression straps):

    • Alpine Grey, 3 lb 3 oz
    • Rugged Multicam, 3 lb 11 oz
    • Expedition Olive, 3 lb 12 oz
    • Guide Slate, 3 lb 14 oz


    Rain Cover / Seam Sealing: 

    •  A rain cover is not needed for main pack bag since it features waterproof material and a watertight closure. Waterproof stuff sacks are recommended for exceptionally rainy conditions, and drybags for submersion or severely wet conditions such as bushwacking or canyoneering.  Seam sealing with Aquaseal, from the outside, will enhance waterproofing for those who frequent very wet conditions.


    Bear cans:

    • Small bear cans can fit in the upper part of the 3900, but with little margin for careless packing.  Other packs like the Divide are a better choice for regular bear can users.



    • Suspension is 500D Cordura and some spacer mesh. Hypalon and 500D Cordura reinforcements
    • Alpine Grey (X21 RC) is a 210 denier plain weave face fabric with a 200 psi PET laminate
    • Rugged Multicam (X33) is a 330 denier Cordura with a 200 psi PET laminate
    • Expedition Olive (X42) is a 420 denier plain weave with a 200 psi PET laminate
    • Guide Slate (X51) is a 500/1000 denier Cordura with a 200 psi laminate
    • Alpine Grey is best for on-trail, lighter duty users and those for whom weight is a priority
    • Rugged Multicam and Expedition Olive are good middle of the road, all around performers
    • Guide Slate is exceptionally durable and suitable for the most rugged and abusive of users


    Additional Accessories:




  • Product Reviews


    Write A Review

    1. Your Search for the Perfect Backpack Ends Here

      This was the 5th backpack I tried in my search for a sub-4 pound not-quite-ultralight pack. The only reason it took so long to get to Seek Outside is that the website is a little confusing. And with a design as unconventional and radical as the fortress, I actually had to do some digging in the forums to get an understanding of what this bag is. That's kinda necessary when you're thinking about dropping 4 hondo on a backpack.

      Anyways, I started with a Mystery Ranch Glacier (too heavy and built with a 1980's mindset of what backpacking is), then tried a Hyperlite 3400 Southwest (beautiful bag, super light, but too short in the torso for me), then went to a Gossamer Mariposa (also too short in the torso), and then tried a ULA Catalyst (nice bag, but the harness moved with the elegance of a slab of plywood).

      If I was a normally proportioned human, my search might've ended with the Hyperlite. But I am 6'6", and most bags, especially stripped down ultralight bags, are not designed for dudes with 25"+ torsos.

      So with great exasperation, I hit the internet and typed in BACKPACKING PACK FOR EXTREMELY TALL DUDES. I had to go deep into the forums, but SEEK OUTSIDE kept popping up. Not only were people saying it works great for tall guys, but that it's the best and most comfortable bag they've ever used.


      This bag is like nothing else on the market. The suspension is clearly the product of a mad genius who cares nothing for convention, or how a bag 'should' look. The suspension is screwed into an external frame with two exposed screws. The hipbelt flops around like the dude on the sewing machine quit halfway through and walked off the job. It just looks crazy.

      But then you try it on, and you understand.

      The bracing elegance of a system that could not possibly get more utilitarian or simple becomes immediately apparent. With only two loose points of connection between the hip belt and the external frame, the suspension is allowed to move with your body. More flex = greater comfort. The Arcteryx Altra is the only other pack I've seen that attempts something like this, but their system is heavier, more complicated, and more expensive ($500+). Seek Outside's suspension is in a class of it's own.

      The materials and craftsmanship of the bag are impeccable. You won't find a better backpack out there at any weight or any price. Bonus points for USA manufacture. And, miraculously, the discreet logo placement. Seems like every brand out there has their logo prominently emblazoned on their bags. Free Advertising, I guess you call it. Seek Outside has chosen not to do this. They've only sewn one small, discreet logo near the grab handle, which is hardly visible when the bag is being worn. In an age where brands are screaming at us constantly from every angle, wearing a bag that is a calm, quiet monument to utility, and not a backwoods billboard, feels like its own statement of ethos.

      If you're a tall dude, be sure to order the frame extensions. I got the 4", and they ended up making for a perfect fit on my lanky clown body.

      on 26th Oct 2016

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  • Warranty Information

    Defects in manufacturing and material for the practical lifetime of the product. Damage due to wear and tear or misuse will be repaired for a reasonable charge.

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  • Other Details

    Main Bag Volume: 3900 (63 Liters)
    Talon Volume: 800 - 1200 CI (13 -20 Liters)
    Weight: 3 lb to 3 lb 8 ounces
    Torso Range 26 Inch: 16 - 21
    Access: Top Loading Roll Top, Talons for quick access