2 Ounces. The difference between being comfortable and not.
We’ve known experienced thru-hikers that avoid some amazing remote backcountry because “the weight required for the long carries would be too uncomfortable with their frameless packs.”
So we asked ourselves, "What if we could design a frame that weighs as much as a sip of water, but could still carry all the necessary gear and weight comfortably, no matter the distance or season?"
That’s exactly what the CS40 Ultra is - the ideal 40L ultralight pack for the ultralight hiker!
It’s comfortable, durable, & stable - even if you are hiking a lot of miles all day!
And this thing is LIGHT.
There are a lot of ultralight backpacks out there that are so minimal that they aren’t even comfortable. But the CS40 Ultra was designed for extra comfort even while maintaining an ultralight weight.
- Comfort Redefined: Unlike other ultralight backpacks that sacrifice comfort, the CS40 Ultra prioritizes your comfort without compromising on weight. Our thoughtful design includes a full frame, functional load lifters, targeted back panel, anatomical shoulder straps, and a wide hip belt for a comfortable fit during extended hikes.
- Ultralight Innovation: We didn't cut corners; instead, we cut weight. The secret lies in the name – CS stands for Carbon Stay. We utilized ultralight Carbon Fiber frame stays, weighing only 2 oz (combined total), to efficiently distribute your load. Functional load lifters ensure weight stays off your shoulders, making every step more comfortable. And then there's the fabric...
- Ultra-Durable Fabric: Our Ultra fabric is as light as DCF but 6 times more abrasion-resistant and twice as strong. It ensures a tough yet lightweight pack for your adventurous pursuits. When the trail gets wild, your CS40 Ultra is up to the challenge.
- Streamlined Design: Embrace simplicity with a minimalistic yet feature-rich design. We kept the essential features you need while eliminating unnecessary bulk. Functional load lifters, stretch mesh pockets, and ample space in the main chamber make this backpack a reliable companion.
Lightweight, durable, & streamlined – the CS40 Ultra is the ultralight solution for hiking without sacrificing comfort.We kept all the best features you need, and got rid of the ones you don’t!
M Torso with M Hip Belt: 27 oz
Features:
Full size, fully padded load bearing hip belt
-targeted cutouts in hip belt foam for breathability and weight reduction
Hip belt pockets with lanyard clip inside
Targeted back panel foam puts cushion where it’s most needed, and leaves voids where it’s not
-targeted cutouts for weight reduction and air movement / breathability (all for comfort)
Breathable shoulder straps with targeted cutouts and breathable ripstop mesh
Adjustable and replaceable sternum strap
Functional load lifter straps
2 carbon fiber internal frame stays
Trekking pole / ice ax retention loops
4 lashing loops on bottom panel of pack
Volumized stretch mesh pocket
Roll top closure allows additional volume
Top compression strap
3 point side compression cords
Self compressing bottom curve to keep your load higher & closer to your back
Internal hydration bladder sleeve and hydration tube port
Generously sized water bottle pockets - fit 2 bottles (smart water bottle size)
Colored white for reduction in heat on contents
Technology:
- Volume: 51L Small Torso Size (39L main, side pockets 2L each, stretch pocket 6L, hip belt pockets 1L each)
53L Medium & Large Torso Size (41L main, side pockets 2L each, stretch pocket 6L, hip belt pockets 1L each) - Main Pack Fabric: Challenge UltraWeave™ 200, - UHMWPE / high-tenacity polyester woven blend, laminated with Challenge RUV™ film
- Hip Belt Fabric: 100D Robic™ nylon diamond ripstop
- Pack Dimensions: S Torso - 21.5" height (plus 10.5" roll top) x 10.75"width x 6.75" depth
M/L Torso - 24" height (plus 10.5" roll top) x 10.75" width x 6.75" depth
(scroll down for hip belt dimensions) - Internal Frame: 2 carbon fiber stays
- Zippers: YKK
- Hardware: Duraflex plastic hardware
- Fits up to: 40" Pant Waist
- Max Recommended Carry Weight: 35 lbs
- Hydration Compatible: This pack can be used with most water bladders if desired
- Warranty: Outdoor Vitals Performance Promise
CS40 Ultra Dimensions
Pack Dimensions:
- S Torso - 21.5" height (plus 10.5" roll top) x 10.75"width x 6.75" depth
- M/L Torso - 24" height (plus 10.5" roll top) x 10.75" width x 6.75" depth
Hip Belt Dimensions (not including webbing):
- XS - 25.5" length, pockets 4.75" x 2"
- S - 27.25” length, pockets 5.5" x 2”
- M - 30” length, pockets 6.5" x 2”
- L - 34” length, pockets 6.5" x 2”
- XL - 36.25” length, pockets 6.5" x 2”
Features
CS40 Ultra on the Uinta Highline Trail
Designing the CS40 Ultra Backpack
How to Properly Adjust & Fit the CS40 Ultra
CS40 Ultra Dimensions
What is UltraWeave Fabric?
Ultra 200 is a 200d laminated fabric that weighs the same as 100d fabric, but is vastly more durable (because it’s about 60% UHMWPE), with a virtually impenetrable waterproof rating (because it’s laminated with RUV film).
Performance:
Tear Strength - ATSM D2261, Warp: 103.1 lb , Fill 133.2 lb
Abrasion - ATSM 3884, 4,400 Cycles
Waterproof - 200+ PSI
*the fabric is waterproof, however the CS40 Ultra Backpack has not been seam sealed & is thus not considered waterproof.
Ultra 200 is in the weight class of 100d Robic nylon, but has twice the tear strength and twice the abrasion resistance as 500d cordura nylon ( which weighs about 3 times as much ).
Ultra 200 Specs:
Weight - 3.5 oz/yd² , 119 gsm
What is UHMWPE?
UHMWPE stands for Ultra High Molecular Weight Polyethylene.
UHMWPE fibers (non-branded Dyneema® or Spectra®) are the lightest and strongest fibers commercially available, with a tensile strength 15x stronger than steel. UHMWPE is created by a gel-spun extrusion process which draws out extremely long chains of polyethylene, aligned along a molecular backbone. This alignment effectively transfers load through the fiber for high modulus and strength.
Easy Return Shipping
Free First Exchange
60 Day Return Window
"I’ve worn over 20 backpacking packs in the past year, and the 27-ounce Outdoor Vitals CS40 Ultra Backpack carries weight the best." -Gear Junkie
"The Outdoor Vitals CS40 Ultra Backpack (shop now) is a new and lighter-than-average contender in an elite group of best-in-class, internal frame ultralight backpacks made with Challenge UltraWeave fabric." -Adventure Alan & Co
"Best Back Panel" in The Best Ultralight Backpacks of 2023, Tested and Reviewed -OutdoorLife
"To me, the 40-liter, 27-ounce CS40 feels like a perfect use case for the fabric—a versatile, do-it-all pack built with some of the toughest material available." -Nathan Pipenberg, Backpacker
revolutionary fabric - featherlight frame
2 oz. That's the difference between being comfortable & not.
There's a problem with most ultralight packs
There’s a significant flaw with ultralight backpacks. They can’t carry a load comfortably.
Packs without frames tend to dig into your body and cause extra fatigue in these situations, but even ultralight packs WITH frames have major design flaws: In order to shed weight, frames are made too short or lack load lifters, failing to create the necessary angles to transfer weight to your hips, also leading to discomfort.
So we asked ourselves, "What if we could design a frame that weighs as much as a sip of water, but could still carry all the necessary gear and weight comfortably, no matter the distance or season?"
And that’s exactly what we did.
CS40 in action
Better Than Cuban Fiber Fabric or DCF
UltraWeave™ 200
It's a tight weave of UHMWPE & high-tenacity polyester that is then laminated with a non-toxic adhesive to recycled Challenge RUV™ film. Compared to DCF 150, it’s 6X more abrasion resistant and 2X stronger (tear resistance and tensile strength.)
Functional Load Lift, Unbeatable Stability
Carbon Fiber Stays
The frame stays in the CS40 Ultra are made of finely tuned carbon fiber for optimum flexibility & stability. They are tall enough for a functional load lift, and conform to your body's motion without restriction.
The best part is, you get all that extra comfort for just 2 oz!
Anatomical Design For Comfort & Breathability
Slotted Foam Padding
Targeted cutouts in the foam found on the hip belt, shoulder straps, & back panel allow the CS40 Ultra to mold with your body seamlessly while allowing for breathability.
This EVA foam will literally wrap around you without resistance!
Curved profile of the main compartment keeps your load distributed correctly
No Load Sagging
Lowered pockets for easier access without removing your pack
Water Bottle Pockets
You could easily fit your entire tent in there if you wanted...
Large Stretch Mesh Pocket
CS40 Ultra BAckpack
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I have tried so many bags...and I don't mean just flop it on willy nilly. I've tried bags from Osprey, Gregory, Hyperlite Mountain Gear, REI, Black Diamond, Arcteryx, Fjallraven, Gossamer Gear, Mystery Ranch and Deuter to name a few over the last few years. I adjust, readjust, shift the weight around, change shoes, and walk probably at least 30 miles in circles in my house before I make my mind up on any anything. This bag is the most comfortable bag I have ever put on. I put 200-300 miles on my last gossamer gear gorilla before trying this but I just still wasn't sure if it was the perfect bag. Once I put this on I cut the tags off instantly...I have never felt so sure about anything! The straps, hip belt and back have the most perfect cushion. The frame sends the weight to my hips so well. The frame also removes easily and can tilt in the bag for airline travel carry on dimensions (I never check a bag). The straps are well spaced at my neck so they don't hurt like the Gossamer Gear Kumo or Hyperlite bags. It is lightweight and carries anything I put in it like a dream. I am so mad I didn't just order this when it first came out...would have saved me a few hundred dollars and so many other tries. I didn't get the strap pockets because they weren't instock and I am leaving soon for a trip but my chicken tramper gear pockets fit well with no modifications. I love the size of the hip belt pockets! They can fit a Lenny and Larry's cookie which is nice! I can reach the water bottle pockets very easily which is usually a struggle for me. I can't wait to take it on my 100 mile!! Thank you Outdoor vitals! This bag is perfection!
I've used this pack for almost two years and over 3500 miles, and absolutely, positively, love it! Even though it's extremely compact, it carries everything I've needed on many weekend backpacking trips as well as two "shorter" thru-hikes and the first half of the PCT. I only replaced it on the PCT because I've managed to rip several holes in the back pocket crawling under blowdowns and didn't want to keep repairing in while on trail. Nothing else has failed.
The fit has been perfect and even when packed with a bear can, ice axe and microspikes plus eight days of food, it carries comfortably. I've literally never had back or shoulder pain while using it. The minimal frame and load lifters do their job wonderfully. The hip belt, back pocket and side pockets have enough room to keep what I need on the outside of the pack, and everything else goes inside. Even the bear canister, once I learned how to do that correctly from an OV video. I plan to keep using it once I repair the holes and use it for many weekend trips to come!
I waited to review this CS40 backpack until I put some miles on the pack. I had first ordered the ShadowLight pack, I really liked the features of that pack but it just didn’t fit me right. Then with the help of your customer support staff I then ordered the CS40 in a completely different sizing and it works perfectly. I love the fit, comfort and size of this backpack all due to your support team. THANKS!
This is a great pack! I love the comfortable harness system and hip belt (with larger sewn in pockets) and find it a dream to carry compared to many other packs I've used. A few touches that would take it to the next level for me: the capacity to close and compress the roll-top down the sides, rather than just on the top of the pack; a better quality stiffener in the roll top; slightly taller water bottle pockets with cinch cords at the top; and a small zippered pocket inside near the top for storing keys, wallet etc.
I am so stoked to have this pack. It exceeded all my expectations in comfort and craftsmanship. It’s a thing of beauty and is so comfortable. My base weight is about 13 pounds and with water and food around 25 and it carries so nice. Looking forward to more trips.
I've only used 'women specific' fit packs previously, so I was a little hesitant to order. The way the hip belt adjusts to contour and fit anyone is a Dream! So Comfy! I'm So Happy to Finally be enjoying a Nice Lightweight Pack :)