Recommended uses:

Thru-hiking

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

$349.00

Quantity

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.
Torso Sizing:

We have three different torso sizes, Sm 16-18", Med 18-20", and Lg 20-22".

If you are on the upper end of a torso size we recommend sizing up.

To measure your torso size you will need to measure from your C7 Vertebrae down to your iliac crest/hip shelf. To get the most accurate measurement, it is best to have someone else measure your back with a flexible measuring tape. The measurement will most likely fall somewhere within our sizing chart. If you do not fall somewhere in our sizing chart shoot us an email and we can discuss custom torso sizing.

The goal for packs with a padded hip belt is to get the belt to ride so that the center line is close to riding on your hip bones. That way you will get the best load transfer to your hips, removing a bulk of the load from your shoulders.

Hip Belt Sizing:

The SL40 comes with a 28" sewn in hip belt with enough adjustable webbing to fit most people.

Frame Size:

The SL40 frame is made out of tubular 7075 aluminum. It uses our standard frame height which is the same as the Long Haul pack. Frame heights are as follows: Sm 20", Med 22", Lg 24".
While the comfort rating on packs is a bit subjective, here is what we have found in our testing of our packs.

The SL40 can comfortably carry up to about 40lbs provided you have the correct torso and hip belt size.

35-40lbs is about the max recommend carrying capacity. If you will regularly be carrying above 40lbs we recommend going for the Wolverine or Big Wild Packs.

30-35lbs will be comfortable for long days on the trail.

Under 30lbs will feel like there is almost nothing in the pack at all.
Our packs are hand-made by us right here in Michigan and are constructed using the finest materials and the best construction methods. These packs are ready to handle anything you can throw at them, and will give you thousands of miles of use.

All stress points are reinforced and bar tacked.

Our packs are very water resistant and are made out of completely waterproof fabric. The optional seam taping will make the packs very water resistant, but a pack liner is still recommended especially for important items.
Side pockets are Ultragrid

Back panel is Ultra200X

Front pocket is made using very durable/stretchy Venom Mesh which is reinforced with UHMWPE fibers, or Ultragird Fabric.

Bottom panel is made out of of Ultra200X in black color.

The front and side panels are offered in either grey Ultra100X or Ultra200X in black color.

Our new packs are made using a more environmentally friendly line of laminated fabrics.

The proprietary Challenge RUV recycled film backing is 100% recycled and 97% UV Resistant. Every yard of ECOPAK™ saves over one pound of CO2, compared to Nylon pack fabric. ECOPAK™ contains no harmful TPU, PVC, DWR or other coatings. CO2 emissions from manufacturing our recycled polyester are: 50% lower than Nylon 38% lower than virgin filmcomparable to organic cotton

Our shoulder straps and hip belt wings are made out of 1/2" thick evazote foams. These are the most resilient and longest lasting foams that we can find. They will give you many years of use without flattening out.
Included Features:

Contoured pack body makes for a glove-like fit. This also makes the pack easier to pack and prevents barreling.

Front pocket made out of very durably and stretchy Venom Mesh or Ultragrid fabric.

Side pockets. Big enough for two 1L smartwater bottles in each pocket.

Drain holes in all solid pockets so they don't fill with rain water.

Very supportive hip belt with great load transfer. Connected directly to the frame. Made out of 1/2" evazote foam.

V-style/outward pull hip belt tensioner.

Ultra comfy S shaped shoulder straps. Made out of 1/2" evazote foam.

Load lifters.

Internal frame featuring twin aluminum stays made out of tubular 7075 aluminum, which won't deform under heavy loads. Frame is fully removable.

Removable foam back pad/sit pad.

Sternum strap.

Two side compression bungies - Fully removable

Bottom strap attachment points. (straps sold separately)

Roll-Top/Dry-bag style top closure with snaps for easy rolling.

Single top strap - fully removable.

3 Top strap attachment points for customized top strap placement.

Attachment points for roll top side compression. (Straps sold separately)

Haul loop.

Bear canister compatible.

Waterproof material.

SL40 Ultra - Internal Frame

Specs

Sizing Guide

Load Carrying Capacity

Pack Construction

Fabrics and Materials

Features