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Recommended uses:


Ultralight backpacking

Weekend trips


Check out our article on our new Ecopak fabrics!


If you're looking for the absolute lightest pack possible without compromising on comfort or features then look no further. The SL40 comes in at 21-22oz depending on size and fabric choice and has a fully featured frame and suspension setup. The SL40 utilizes two tubular aluminum stays, load lifters, and a thickly cushioned hip belt and shoulder straps for max comfort on trail. 


Other Highlights Include:

  • Two easily accessible water bottle pockets big enough for two 1L smartwater bottles in each pocket.
  • A large mesh front pocket for storing wet gear or anything that you want accessible throughout the day.
  • Side compression bungees for squishing down the pack's capacity and for trekking pole storage.
  • A modular top strap setup, which means you can use a single top strap, a Y strap, or a double top strap and swap them out as needed. The double top strap is our preferred method for bear canister storage.
  • A removable frame so you can turn the pack into an 18.5oz frameless pack good for loads up to 25lbs.
  • Bombproof construction utilizing quadruple stitched, flat-felled seams throughout. All stress points are also bar tacked.


The SL40 is available in Ultra100X or Ultra200X, both of which have a very durable UHMWPE face fabric. This fabric is much more durable than your typical nylon or polyester fabric, but is also much lighter than other 100 and 200 denier fabrics. It is also laminated which makes the fabric fully waterproof. This makes for a very durable, light and water resistant pack. 


This medium capacity ultralight pack has a max internal capacity of 40L and compresses down to a compact 25L when rolled all the way down. The outer storage pockets add about 10L of extra capacity making for a total of about 50L of storage space in the pack.


The SL40 is a very comfortable and easy to use pack with a very capable frame and suspension system that can handle up to 40lbs if you need it to. Loads of 35lbs or less  are optimal and will feel like you are floating down the trail.


Ways to get the pack even lighter. 

  • You can use a sleeping pad/sit pad behind your back to replace the back pad which will reduce the pack weight by .8oz. 
  • Remove the frame from the pack to turn it into an ultralight frameless pack weighing only 18.5oz and you'll be good for loads up to 25lbs.
  • Remove the side compression bungees for .2-.3oz weight savings.
  • Trim excess webbing for an additional .1-.3oz weight savings depending on how much you are able to trim.


All of our packs are made to order. Check our current lead times here.

SL40 Ultra - Internal Frame

  • 40L specs:

    Dimensions when empty:

    • 40L internal/50L total capacity when utilizing outer storage pockets
    • Minimum Capcity: 25L internal/35L when utilizing outer storage
    • Bottom Circumference: 32.5"
    • Top Circumference: 34.5"
    • Unrolled Height: 35"

    Packed/Rolled Dimensions: (Used to calculate internal volume)

    • 32.5" lower circ
    • 34.5" upper circ
    • 29" height

    Weight breakdown:

    • Fully loaded pack weight: 21.5oz med
    • Pack body - 17.6oz 
    • Side compression bungies - .2oz per pair
    • Top strap - .5oz
    • Aluminum stays - 1.9oz (med)
    • Foam back pad - .7oz
    • Pad lashing - .14oz
    • Sternum strap - .5oz

    Note that these weights are based off of the Ultra100X body fabric. Ultra200X adds about .5oz. The Ultragrid front pocket option adds about .2oz to overall pack weight. The black shock cord color is the lightest option and the other colors add about .2oz to overall pack weight. 

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