Katabatic Gear Onni V40 65L Backpack Review

The Katabatic Gear Onni V40 65L is a durable high volume backpack made with waterproof XPac fabric
The Katabatic Gear Onni V40 65L is a durable high volume backpack made with waterproof XPac fabric

The Katabatic Gear Onni V40 65L is a 34-ounce rolltop backpack that’s designed for challenging multi-day backpacking trips. It’s made with a waterproof laminate called V40 (XPac) which is slightly heavier than cuben fiber but less expensive and more abrasion-resistant. Katabatic Gear offers all of their packs in two fabrics, High Tenacity Nylon and V4o, which is made for people who are really rough on their gear. I review the V40 version of the Onni below, but the nylon version is virtually identical.

Katabatic Gear Onni V40 65L Backpack


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The Katabatic Gear Onni V40 65L backpack is a rugged and durable ultralight-style backpack with a ventilated back panel made from a waterproof and abrasion resistant ultralight fabric called V40 XPac. Newly released, it needs a few minor tweaks to make it a truly great pack, like taller water bottle pockets and a wider hip belt to carry heavier loads.

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Why would you want the V40 XPac version of the Onni 65L instead of the nylon version?

  • If your trips involve a combination of on-trail and off-trail hiking through pack-ripping vegetation or granite
  • If you hate using a backpack cover in rain and want a pack made of waterproof fabric
  • If you think cuben fiber packs are overpriced and want the same benefits with better durability
  • If you’re sick of replacing high tenacity nylon or robic ultralight backpacks because you rip them to shit every year

Katabatic Gear used to make a cuben fiber pack called the Helios 55 (see the Section Hiker review), but the demand for this cuben fiber backpack was low so they’ve stopped making it. Too bad, because the Helios 55 was a fantastic backpack. The Onni 65 (really 68 liters) is very similar but performs somewhat differently because it has a higher volume and deeper dimensions, which put more of a strain on the hip belt.

Specs at a Glance

  • Volume – 68L size medium
  • Weight – 34 ounces + 2 ounces for optional hip belt pockets (40 ounces actual)
  • Materials
    • V40 – 420D Nylon with laminated 0.5 mil PET film. PET film is more waterproof and durable than PU coatings
    • V40T – Used for bottom of pack. 420D Nylon with laminated 0.25 mil PET film and 50D polyester backing for increased durability.
    • Cordura Spandex Blend – hip belt pockets
    • Cordura – water bottle pockets
    • Aluminum 6061-T6 Stay – Contoured high strength Aluminum
  • Sizes
    • Small fits torso length: 15.5 – 18.5″
    • Medium fits torso length: 17.5 – 20.5″
    • Large fits torso length: 19.5 – 22.5″
  • Mfg recommended Load: 35 pounds (more like 25 pounds)

Internal Storage and Organization

The Onni V40 65L is organized like most roll-top ultralight-style backpacks, with side water bottle pockets, a rear mesh pocket, and side compression straps. Now 65 liters (it’s actually 68 liters in a size medium) might sound like an enormous volume, but Katabatic Gear, like many smaller manufacturers computes their interior pack volumes differently from most mainstream pack makers. Instead of just measuring completely closed pockets, disregarding any added extension collar volume (which is the industry standard), they include the extension collar and open pocket volumes in their total. Keep this in mind when comparing the Onni with packs from other manufacturers who may compute pack volume differently.

The Onni 65L’s storage is broken down as follows.

  • Size medium (68L)
    • 42L main compartment
    • 12L extension collar
    • 5L side pockets
    • 9L back pocket

Main compartment

There’s no denying that the 65L Onni is a high-capacity pack, even if you don’t count the volume of the open pockets. But it’s a roll-top which makes it easier to shrink the pack’s volume when you don’t need it. I like having a pack this size for cold weather hammocking or winter backpacking because it’s big enough for me to fit extra insulation and layers without having to go crazy trying to jam them into a smaller volume pack. It’s also handy for trail work trips and multi-sport trips like fly fishing or packrafting when I need to carry bulky sport-specific gear like waders, a wet suit, or a PFD. A larger pack like the 65L Onni is also handy if you need to carry a bear canister (a Garcia 10L Bear Canister fits vertically with room to spare.)

The XPac interior has a shiny PET coating
The XPac interior has a shiny PET coating

The interior of the main compartment is coated with a glossy polyethylene (PET) which according to Katabatic Gear is more durable than a PU coating. This means that you don’t have to carry a pack cover since the fabric can’t absorb water. The seams are not taped but sewn, but there’s little chance you’ll have significant leakage unless you stand the pack in a puddle or drop it off the side of a packraft. Katabatic Gear still recommends the use of a liner, though. I use a white contractor’s bag inside the Onni, primarily to make it easier to see my gear against the white plastic since the inside of the pack is grey and it’s hard to see gear buried deep in the pack.

The Onni doesn’t have an internal hydration pocket for holding a bladder, but there are three webbing loops at the top of the back panel to hang a reservoir along with hydration ports behind each shoulder. The central stay is held in place by a velcro topped channel, so you can pull it out and bend it.

The two sides of the roll-top opening are held together by three pairs of small but powerful magnets glued into the hem. The magnets are strong enough to interfere with a hand-held compass if it comes in close proximity to them, so this isn’t a feature that I particularly like. Katabatic Gear doesn’t believe it to be a significant issue, but I’ve had problems with backpack magnets and compasses in the past and have no inclination to revisit them. You can easily cut the magnets out and repair the holes with a dab of Shoegoo, without affecting the roll top performance.

While it's easy to reach back and pull out a water bottle, the pockets are a little to short for holding Smartwater bottle unless you hold them in with a compression strap.
While it’s easy to reach back and pull out a water bottle, the pockets are a little to short for holding Smartwater bottles unless you lash them in with a compression strap.

Side pockets

The Onni V40 65L has a pair of side pockets made with what Cordura instead of V40. The pockets are large enough to fit two x one-liter bottles and it’s easy to reach back and pull them out or replace them while wearing the pack. If you prefer using Smartwater bottles, they have a tendency to fall out of the pockets when you’re scrambling or you put down your pack for a rest because the pockets aren’t tall enough. Try using a shorter bottle.

Alternatively, the side bottle pockets have a compression strap that can be routed outside or inside the pocket (there is a female connector inside the pocket and one on the outside), so you can strap a tall bottle in place by running the strap outside the pocket. But forget about reaching back and pulling it out to have a drink.

More on the Onni side compression straps below in the section on attachment points.

Back mesh pocket

The back mesh pocket is quite sizable (9L) and made with heavy-duty mesh to resist tearing, even when hiking off-trail. The top is held closed by a webbing strap that runs over the roll top. The mesh pocket is so large that I can store my stove and cook system,  tarp, tent stakes, and water filtration systems (wet and smellies) and still have room for any layers or food I want to carry close at hand during the day.

Durable mesh back is very large providing storage for wet and smelly items
Durable mesh back pocket is very large providing storage for wet and smelly items

Optional hip belt pockets

You can order optional hip belt pockets with this pack. These are long, large, and close with a beefy YKK zipper. They’re faced with a stretchy softshell fabric (a Cordura Spandex blend). The front of my hip belts take more of a beating on east coast bushwhacks than any other part of a pack, so I wish these were made with a tougher fabric like the V40. On the flip side, they are an option so you can do without if you’re going to destroy them anyway.

External Attachment and Compression System

The Onni 65L has two tiers of long compression straps on the sides of the pack which are the primary external attachment points on the pack. They’re well sized for lashing packraft paddles or fishing rods along the side of the pack and resting in one of the side pockets.

While the bottom tier of compression straps can be used to hold the sides of the roll-top closed (the way many roll tops work), they’re best used for side compression when filling the backpack tightly with a lot of gear. The sidewalls of the main compartment have a tendency to bow out into the side pockets if you wedge an oversized stuff sack (for example) into the base of the pack. The bottom compression straps can prevent this and preserve the side pockets’ volume if you tighten them before you pack the pack. Otherwise, it’s difficult to compress a load on the Onni V40 65L after it’s been packed.

There are 3 ways to route the bottom compression strap: inside the pocket (not shown), outside the pocket (left), and holding down half of the roll top.
There are 3 ways to route the bottom compression strap: inside the pocket (not shown), outside the pocket (left), and holding down half of the roll top (right).

If you want to rig up your own external attachment system around the back of the pack (over the mesh pocket), there aren’t any gear loops or good attachment points to anchor your own cordage. However, like the Helios 55, the compression straps on the Onni 65L are reversible with male and female ends that connect over the rear pocket. These are good for strapping snowshoes to the back of the pack, for instance.

The shoulder straps don’t have daisy chains sewn to their fronts, which makes hanging gear (GPS, InReach, Whistle, Map Pocket, Camera Pocket, etc) off troublesome. There are a few fabric loops where you could hang small water bottles or bear spray from the shoulder straps, but they’re not sufficient for much else. I managed to hang a whistle and camera pocket from mine with some extra attachment hardware, but prefer shoulder straps with daisy chains sewn on the front to make this easier.

The pack also has four elastic cords w/cord locks positioned along the back mesh pocket for strapping trekking poles to the pack. They’re functional for trekking poles, but I prefer having a real buckle for attaching an ice axe shaft. Axes and elastic cords will be ripped off your pack when they catch on an overhanging branch. Ask me how I know.

The frame of the Onni 65L has a subtle curve to it to help ventilate the back
The back panel of the Onni 65L has a subtle curve to it to help ventilate the back

Backpack Frame and Suspension

The heart and soul of a backpack are determined by its frame and suspension system. The Onni 65L frame has two parts, a rigid foam back panel, and a center aluminum stay. The stay terminates inside the hip belt, which is sewn to the base of the backpack. The foam pad is slightly pre-curved which helps with ventilation, but stops short of an articulated lumbar pad. A pair of load lifters are attached to the top of the foam panel which is stiff enough to be effective if you crank down on them to re-angle the pack.

The front of the backpack facing the wearer is covered mesh that’s layered over a ridged and perforated foam panel. It works surprisingly well at preventing your shirt from becoming soaked.

The hip belt is sewn directly to the base of the frame, which limits your ability to swap in different sizes, but normally provides very good load to hip transfer. The Onni 65L hip belt isn’t very stiff however and is really just a thin piece of fabric covered by spacer mesh at the point where it connects to the frame and the pack’s back panel.

When the Onni is filled with 30-35 pounds of gear, water, and food, which is its recommended load limit, the hip belt has a tendency to buckle under the load and slide down over your hips. I recommend that Katabatic Gear widen the back of the hip belt where it connects to the frame as this will prevent slippage, while still providing a good hip wrap to accommodate many hip shapes. It really is that simple.

The question arises, why does the hip belt buckle on the Onni and not the Helios 55 (no longer made), which used a near-identical frame and hip belt system. I think the answer lies in the Onni’s larger pack dimensions. It has a deeper and wider packbag with a larger rear mesh pocket that creates a very different loading profile than the Helios, which was smaller in volume and aligned more closely to the hips and back. Based on my experience testing the Onni 65L, it does not live up to is 30-35 pound load rating. Unfortunately,  I really can’t see any value in carrying a pack this large with a lower weight rating (25 pounds) and suggest you look at packs from other manufacturers in the same volume range if you plan to pack heavy.

The Katabatic Gear Onni V40 65L is high capacity pack designed for multi-day backpacking trips in the backcountry
The Katabatic Gear Onni V40 65L is high capacity pack designed for multi-day backpacking trips in the backcountry.


The Katabatic Gear Onni V40 65L backpack is a rugged and durable ultralight-style backpack with a ventilated back panel made from a waterproof and abrasion-resistant ultralight fabric called V40 XPac.While the Onni 65L (68 liters in a size medium) is similar to the Helios 55 (no longer available) that Katabatic Gear sold previously, the hip belt of the pack has a tendency to collapse under the 30-35 pound loads recommended by the manufacturer. As these loads are the minimum one could reasonably expect from a pack of this volume, I’d recommend that you consider other lightweight and durable backpacks in the same volume range including the ULA Circuit or the Seek Outside Divide. I have not had the opportunity to test Katabatic Gear’s other new backpacks including the Onni V40 50L (really 51L), which may in fact perform quite differently than the 65L (really 68L) because it has smaller pack dimensions and can carry less gear.


  • V40 XPac fabric is tough and effectively waterproof
  • Roll top closure helps shrink volume if not needed and provides top compression
  • Huge, durable back rear pocket provides storage for wet/smelly gear


  • Hip belt collapses under load
  • Magnets sewn into roll top interfere with compasses
  • Heavier than website spec weight
  • Unisex only

See Also:

Disclosure: The author received a sample backpack for this review.

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  1. Great review Philip! Sounds like they still need to dial in the design a bit. Really appreciate that you use the gear before reviewing it. Your attention to the details important to hikers really shines through. Must have sucked to have that much weight slide off your hips .

  2. I really appreciate this review since this specific pack is one I am/was looking at purchasing. Currently I am using an older, beat up Golite jam 50 that I’ve had for years now. I’m trying to find something similar, maybe a bit bigger, without spending a fortune. Thanks!

  3. Wow, thanks for the links. Much appreciated!

  4. Thanks, Philip, for your candid feedback. We are constantly looking for ways to improve our gear and we value the input from our customers and media reviewers. We will certainly keep your comments in mind, specifically with the hip belt, as we make future pack iterations.

  5. “Hip belt collapses under load”, wow, that’s clearly a big mistake and this for at leat 300 dollars..

  6. I appreciate these reviews! I’m reading pack reviews closely these days, as i’m (somewhat reluctantly) looking for a lighter alternative to my trusty, but just-a-little-too-heavy (just over 5 pounds), external-framed Kelty Tioga 5500.

    It’s really been the only pack i’ve ever carried on multi-day hikes. Had the original one back in the 70s. When i got back into hiking after some years away from it, i got the updated version back in 2013. I’ve never had any issues with strap rubbing or chafing, even with heavy (40+ lb.) loads. It’s always comfortable, even at the end of a long day. Mesh back panel keeps the thing off my back. Just about the only thing that wears or breaks is the fabric around the grommets at the top of the shoulder straps (used to attach the straps to the frame) starts to tear and pull out after a few hundred miles.

    Another reason i love this pack is the organizational capability. The main, top-access pocket has an extendable sleeve at the top. There’s a water-bottle compartment sewn into the top of the back of the main compartment. There’s a zippered, bottom pocket with a removable flap/divider that separates that space from the main compartment. There’s a front pocket on the outside of the main compartment. One one side, a large, zippered, long side pocket with a sleeve between the pocket and the side of the pack. On the other side, three more pockets; the top one open-topped with another smaller pocket piggy-backed that is zippered. Another pocket below those with a zippered top. The flap that covers the top of the main chamber and, usually, the outside front pocket, is two-layered with zippered access to that space with enough room for maps, jackets, whatever.

    I’m kind of wedded to this organizational system, yet realize that all this extra fabric, zippers, etc. is also what’s mainly responsible for the “extra” weight compared to packs that are primarily one long chamber with two small side pockets and maybe a mesh front pouch.

    Most internal frame packs have just never felt right to me, even walking around the store with bean-bag weights and such. Ideally (for me), Kelty would redesign this pack with narrower gauge frame tubing, perhaps titanium, use a lighter weight fabric (instead of the old school, bombproof Cordura), maybe downsize the zippers. Seems possible to easily cut, perhaps, 1–2 pounds off the same design.

    The Vargo ExoTi 50 comes close to this, but lacks the pocket diversity. The Mariposa 60 has a similar pocket system, but the framing and suspension looks like a potential weak point. I actually ordered a Granite Gear AC Blaze 60, which is a cool pack, but i can’t imagine organizing a longer trip with just the two small side pockets, so it’s going back.

    It appears i’m not the only one that has gone on this quest. Alex Hitt in a post titled, The Search for the Perfect Pack, on his 40 Years of Walking Blog, details a similar journey. As of the last 2015 update, he had settled on a slightly modified, internal-framed Elemental Designs Kalais.

    Any suggestions or ideas for packs i might consider would be greatly appreciated! Or if anyone has connections at Kelty…

    • Try the external frame packs from Seek Outside. Unlike any external frame you’ve ever carried

      • Thanks for the suggestion! Seek Outside has recently caught my attention during recent sleuthing. It might have been your review of the Unaweep 4800 that put them on my radar.

        From the few other reviews i’ve checked, this looks like a nice pack and is one i’m considering. At plus/minus three-ish pounds depending on accessories, it falls between my five-plus-pound Kelty and the 2-ish pound superlights, which i think is a reasonable compromise for me.

        Downsides are the single, undivided main compartment (no divided-off bottom compartment like the Kelty), and only the two side pockets (though the Talon add-on could substitute for those).

        What i’d really like is a lighter weight version of the Tioga with the same layout, but that ain’t gonna happen, so i’m just going to have to figure out what compromises i can live with. Change is supposed to be good, right? At the moment, for external frame, the contenders are shaping up to be the Unaweep, the Vargo, and the Exos.

  7. How do you like this pack compared to a hyperlite mountain gear or a zpacks? Im in colorado and want to support a local company. This pack looks really appealing. Thanks!

    • If you read the review, I don’t think much of this particular model because the hip belt is under-classed for its max load. Otherwise its a fine pack and the smaller 40L versions handle much better.

      But I prefer HMG packs, specifically the 2400 Southwest and 3300 Southwest packs the most. They fit me perfectly. When push comes to shove, that’s really the main factor you need to focus on. They’re all great and very durable packs.

      • Ive been curious about how the HMG packs have no load lifters and if that effects the pack comfort towards the higher weight limits. Any thoughts? Or would a average carrying weight of 25-30 pounds work for a HMG?

      • I wish they were on the 4400 but the 2400 and 3400 are just fine without them.

      • And would you say the smaller version of the Onni vs the hang windrider is comparable? Or Hmg all day? Thanks for your responses too they have been really helpful

      • I don’t really trust the mesh on the Windrider. The holes are too big. I use a Southwest since it has no mesh. If mesh is important to you (i think it’s way over-rated) the Onni has tougher mesh.

  8. Hi, great review as usual.
    I was wondering if you have seen the Onni 50L Liteskin? Several people online have mentioned this is very similar to the Helios 55 and I was curious if you agreed with this?
    Since they don’t do the Helios could this be the next best option?

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