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.
"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 only used the CS40 on one trip so far - a 37mi hike on the AT in mid-September. It fits nicely and carried my gear (baseweight, water, and food at <27lbs) with no problem. I am 63 yrs old, 5'11 and 160lbs, so lightweight and comfort are important. The CS40 accomplished that. The only issue was the bear cannister. It fit but was very tight and consumed lots of space (but that's not the pack's "fault"). The side pockets are awesome and you can easily reach your water bottles. The only reason I did not give it a 5 was that I have not walked that part of the trail with that weight with my old pack to draw an accurate comparison. Also, i a bit concerned on how well the mesh stretch pocket will hold up. But only time will tell. And yes, that is the Altitude Sun Hoodie in the pictures.
I've had this pack for a couple months now, and have used it on a 3 night backpacking trip and a couple SAR day trips.
The good: It is comfortable, and mostly fits. I'm a slim, straight 5'6" 120lb gal, and a size small pack with the smallest hipbelt works well, and actually cinches down with room to spare. The back panel is comfortable, the frame doesn't dig into my tailbone, and the pack doesn't sag lower when packed (woohoo!). The load lifters work well, and the shoulder straps didn't give me shoulder or collarbone pain. All that said, I've only hauled loads up to 23 lb so far. The mesh pocket stretches generously. The side pockets are accessible without taking the pack off. The interior hydration sleeve accommodates (barely, with a lot of fiddling) a platypus big zip 2L. The white fabric helps with visualization while digging in the pack looking for stuff.
The not so good: the side compression straps aren't placed low enough on the pack, so only the top half of the pack can be compressed, and less bulky loads can't be evenly stabilized. They also make strapping anything on the sides difficult/not possible. Additionally, I really wish there was an ice axe loop and cinch. Also, the hipbelt pockets are nearly worthless. They are an odd square shape, take two hands to zip, and don't accommodate a phone. I have been stashing a buff, headlamp, or snacks in them, but the opening is small enough it's hard to get fingers in, without gloves on.
Personally, I would love a j zip for better access to the interior of the pack in less than ideal weather, and a different shoulder strap option, as these are a little wide and straight for my narrow shoulders.
Overall this pack is definitely a keeper, since it's lightweight and actually comfortable (thank you OV!), but really wish for some tweaks in design and functionality.
Gunna be testing it out this weekend but it's definitely my favorite backpack so far. supper light fits all my gear in it and will be understanding more about carrying lighter than heavypack this is well built.
After receiving my CS40 pack, I quickly put my gear inside to see how it fit. First off, everything fit inside as I had hoped. Secondly, and this is the most important part. I slid the pack on to by back and was presently surprised at at well it fit, and what a good fitting pack is supposed fit. Waist belt was a bit snug, but im also in the process of training for JMT next summer so I'm not worried about the waist belt being to snug by then.
Since then I took the pack for a 6 mile trial training walk around my neighborhood. Amazing how well it felt an my back, no pressure in the wrong places, no nagging shifting of the pack to feel better. As the title sais it never felt so good. I can not wait to actually get out on the trails soon for training and put the miles into it to truly put the pack through its paces.
Finished a 7-day trip in harsh conditions with the CS40 backpack: It is perfect. Yes, it is very light weight, but it’s best feature is how comfortable it is to wear: I’m an old guy in my late 70s so pack weight is a major factor for me. The design is not only light-weight, but it is able to distribute the pack weight perfectly over the body. This pack is a replacement for a famous-brand pack that did not seem to fit me well. The difference in comfort is amazing. The CS40 is plenty large enough for a week-long trip, even in harsh condition that require extra layers of clothes. Outdoor Vitals, hit a home run with this great back-pack!
