Fortress 4800


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Fortress 4800


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    The Fortress is a no holds barred ultralight load hauler.  Featuring our most waterproof design with rolltop closure and two water bottle pockets, the Fortress utilizes our Talon Compression system to change the organization of the pack to match the adventure at hand. 

    The Fortress is elegant in simplicity.  The packbag is as water resistant as possible, and organization is added as needed through Talons, Top Lids, or Hipbelt Pockets.  This pack has been used for Artic expeditions, ski mountaineering, backpack hunting, and general backpacking.  Our oldest and most tested pack design, the Fortress has proved up over many years of tough trips.

    Handmade in Grand Junction, Colorado, USA.

    Why it's Compelling

    • Minimum Trail Weight - 3 lbs 10 oz 
    • Volume - 4800ci | 79 L (not counting pocket volume)
      • Base Talon adds around 800 ci, Merlin adds 1400 ci
      • Two side water bottle pockets sized to hold two Nalgenes each.
    • Load Range - 200+ lbs
    • Field Adjustable Frame Height
      • 24” frame for light to moderate loads
      • 26” frame for moderate to heavy loads
      • 28” frame for heavy loads or long torsos.
      • Quick tool-less field adjustment via Frame Extensions.
    • Breakaway Carry allows for easy meat packing.
    • Made in Colorado by people who are passionate about the same pursuits you are.  


    • Weather resistant design:
      • The Fortress is our most water resistant design.  No zippers, Breakaway Platform (as opposed to Unaweep on Integrated Platform) reduces packbag stitching.
      • X-Pac packbag fabric is forever waterproof.
      • Rolltop closure is highly water resistant.
      • No raincover needed, though Seam Sealing and / or drybags for sensitive gear are smart in very wet conditions.
    • Organization:
      • Large side water bottle pockets accept two Nalgenes each, or a tripod / spotting scope.
      • Tab loops at top of frame panel make it easy to hang a water bladder between the frame and packbag.
      • Optional hip belt pockets, top lid, and Talons for more organization.
    • Gatekeeper Compression:
      • Six side straps (three on each side)
      • Two bottom straps
      • One over the top strap
      • Load shelf
      • Ladder load shelf anchors allow you to raise the load and prevent sagging.
      • Compression straps are moveable and removable.  Add extras if you need them.  Connect two together to make extra long straps for big or awkward loads.
    • 4-Way Forward Pull hipbelt closure with single center buckle allows top / bottom tension adjustment, easy to use.
    • 6061 T6 Aluminum Revolution Frame (Patented)
    • Two removable aluminum horizontal cross stays.
    • Breakaway Carry - can carry a dry bag or pack meat between packbag and suspension.

    Load Rating - 200+ lbs

    Our frame will support over 300 lbs in vertical load.  YOUR max load will be determined by your body, not by the pack.


    • Select options desired and add to cart.  A live inventory feed will tell you if the pack is in stock or if there is a lead time.
    • Hipbelt sizes run true.  Size up if you winter hike, size down if you slim down on long trips in summer.
    • Frame Extensions - to learn more, click the Instructions tab, or read Which Frame Height Is Right For Me?
    • Lumbar Pad - Recommended if you don't know if you'll need it or not.  Some people really need it.  Some people really don't.  Try it and return it if the fit is better without.
    • Top Lid, Talons, Hipbelt Pockets - gear organization is a personal preference.

    Detailed Specifications 

    • Weight
      • Shipped Weight - 3 lbs 15 oz
      • Minimum Weight - Without cross stays, minimum compression - 3 lbs 10 oz
    • Volume
      • Packbag - 4800 cubic inches | 79 L
      • Side Pockets hold two Nalgenes each.
    • Dimensions
      • Top Circumference - 43"  |  109 cm
      • Bottom Circumference - 42"  |  107 cm
      • Unrolled Height - 38"  |  97 cm
    • Materials
      • X-Pac Fabric - Packbag is made from VX42 X-Pac, a 4 ply laminate featuring a 420 denier nylon face fabric permanently bonded to a PET (Mylar) film with an X-Ply polyester yarn for bias stability and an inner taffeta liner for brightness and stitch retention.  This creates a lightweight yet durable fabric that is waterproof to over 200 psi for the lifetime of the fabric.
      • 500 Denier Cordura - Side pockets and many suspension components feature 500D Cordura for strength and abrasion resistance.
      • YKK AquaGuard® Zippers - #8 size YKK AquaGuard zippers are durable, highly water repellent, and easy to use.
    • 4-Way Forward Pull Hipbelt Closure - Allows variable top and bottom tension to adjust fit to body type or relieve pressure points.  Is very secure and easy to use, and easy to tighten or adjust while under load.  Route the belt webbing through one slot in the center buckle to allow it to even top / bottom tension.  Route webbing through both slots to separate the top / bottom tension adjustment.

    Included with Backpack:

    • Eight compression straps (removable)
    • One over the top compression strap
    • Load shelf
    • Field repair kit


    Check out our Backpack Fit & Instructions Page to find many videos that cover common questions and give in depth information. 

    Backpack Instructions


    A good fit requires several things:

    • Correct Torso Length
    • Frame height suitable for your torso and load ranges
    • Correct Belt Size
    • Correct Belt Adjustment (high, medium, or low grommet)

    After fitting the pack to your body, you can tune comfort with three hard breaks.  These adjustments drastically change the feel of the pack and users typically have a strong preference for each of these.

    This is good because it speeds the adjustment process....if you don't like the way the pack feels change one of these and it will feel very different.

    These cause hard breaks in the feel of the pack:

    1. Lumbar pad or no lumbar pad.
    2. Captured or floating hipbelt.
    3. Captured or floating harness.

    Torso Length

    Achieving a good fit starts with the correct torso length.  To read in-depth about torso length, adjustable frame height, and load ranges, see Which Frame Height is Right for Me?

    Torso length is the distance from C7 (the prominent vertebrae at the base of your neck) down the spine to an imaginary line drawn connecting the points of the hips (iliac crests).  Common measurements for a 6' tall male would be 17 to 19", while a 5'5" female may be 15 to 16", though these measurements vary widely based on body composition.

    Match your torso length with the correct frame height for your expected load ranges.  One advantage of our Field Adjustable Frame Height is that you can shrink the pack down for day loads and expand the height for heavy loads on the fly.

    How to know your pack adjustment is correct:

    1. With 25 lbs in the pack, you can rest your index finger on C7 and touch the top of the harness with your middle finger (i.e. only a finger width between C7 and harness).
    2. With heavy weight (75 lb +) in the pack, you can take weight on the shoulders OR transfer it all to the hips by adjusting the shoulder straps and load lifters.
      1. Loosen shoulder straps and tighten load lifters transfers weight to hips.
      2. Loosen load lifters and tighten shoulder straps puts weight on shoulders.
      3. This allows you alternate resting hips or shoulders, whichever is tired.
      4. If you CAN’T do this then the shoulder harness is too high or too low.

    Frame Height

    Frame height preferences vary person to person, so be sure to experiment and see what YOU prefer.

    • Shorter frames give less shoulder lift (upward angle to shoulder strap, lifting the harness), but they give you more freedom of movement to look sharply upslope, and snag less on overhanging branches.

    • Taller frames give more shoulder lift, but also can limit head movement and snag more.

    In general users often prefer shorter frames for lighter loads and taller frames for heavier loads, but preferences vary.


    The Ear Guideline

    People wear hipbelts high and low.  This can change their effective torso height and throw off the guidance above.  So using the frame height relative to the ear can be a better guideline in some cases.

    • Below the ear is fine for lighter loads.
    • Low ear works well for middleweight loads.
    • Low/mid ear or above works well for heavy loads.

    Belt Size & Adjustment

    The padded portion of the hipbelt should wrap around the front of your hipbones, yet not so far that you run out of webbing adjustment.  Consider seasonal use and clothing worn when selecting your size.

    Most users want to center the hipbelt over the points of the hips.  This is an excellent starting point for belt position on the body. 

    • Wearing the belt too low can impede leg movement.
    • Wearing the belt too high can cause discomfort in the waist.
    • Note that hard edged belts can cause pinching or hard spots when worn under a hipbelt, especially for those with bony hips.  An elastic belt or no belt can make a big difference.

    Hipbelts are connected to the frame with a grommet and screw.  The Hipbelt has three grommets - a high, medium, and low.  

    Many users prefer the highest position to raise the frame up relative to the belt, but again preferences are all over the board here.  If the belt isn’t comfortable try a different position.

    Hard Breaks in Adjustment

    Lumbar Pad vs No Lumbar Pad - you will probably strongly prefer one or the other.  Telephone pole builds (flat back, straight up and down) often prefer no lumbar pad, while curvy or beefy builds often prefer the lumbar pad.

    Captured vs Floating Belt - Captured can only be done WITH a lumbar pad.  Floating can be done WITH or WITHOUT a lumbar pad.  Less significant than the lumbar pad in changing the feel of the pack, users still usually prefer one or the other.  Captured keeps the hipbelt upright and can help prevent the 3D mesh face from collecting snow or pine needles.

    Floating vs. Captured Harness -  the straps that adjust torso height have holdfasts on the suspension that secure the harness.  Two adjustments can be made to free the harness.

    To free the harness:

    1. Reroute the torso adjustment straps (1” webbing) so it does not pass through the holdfast tab on the Frame Panel or behind the cross stay on Integrated packs.
    2. Reroute the webbing so it passes through only one side of the two sided triglide on the back of the harness.

    These two changes move you from a captured / stabilized harness to a floating harness.  People who prefer a floating harness often roll their shoulders forward when hiking, and the extra give in the harness system conforms to their upper back better.

    • Captured Harness - helps control side to side sway with heavy loads, less reliance on load lifters (can run load lifters looser).
    • Floating Harness - side to side sway with heavy loads is controlled with the load lifters.  Load lifters are usually run tighter than with a captured harness.

    One final tip - Users who prefer no lumbar pad often prefer a floating harness.


    Q: Is your pack waterproof?

    A:  No.  We use waterproof or highly water resistant fabrics and highly water resistant zippers, and highly water resistant rolltop closures, but water can seep in through stitch holes in the seams.  In rain this usually isn't a concern.  If you're packrafting on Kodiak or doing a two week trip in the Olympics during rainy season then you might want to seam seal your packbag.

    Q:  How do I seam seal my packbag?

    A:  Seam Sealing a Backpack

    Q:  I'm having trouble getting my pack to fit comfortably.  What should I do?

    A:  If you've watched the fitting video and read the instructions on the instruction tab, then you should call us at 970-208-8108.  Adjustments can be tricky, but we've got a really good success rate at getting the packs to work for a wide variety of body types.

    Q:  How do I know which pack best fits my needs?

    A:  That's a deep subject....take a few minutes to read this article - How to pick the right backpack hunting pack (for YOU).


    Lifetime against defects in materials and craftsmanship. Normal wear and tear excluded