Atom Packs “The Mo” 50 Backpack Review

Atom Packs The Mo 50 Backpack Review

The Atom Packs “The Mo” 50L is a beautifully crafted internal frame backpack made across the pond in England. Weighing 32.1 oz (910g) and made with waterproof Ecopak EPX200, it’s a roll-top backpack that’s loaded with features and pockets that will appeal to most thru-hikers and hill walkers. I’ve been particularly impressed with that pack’s frame and suspension system, which is capable of carrying surprisingly heavy loads with great comfort and ease. If you’re looking for a highly functional backpack that has a unique edge to it, check out Atom Pack’s, “The Mo.” They also provide no-hassle shipping to the USA.

Specs at a Glance

  • Model: Stock Pre-Built; also available as a custom pack
  • Volume: 45L in main body + 2.5L in each side pockets + 5L in front mesh pocket (not counted in total)
  • Weight: 32.1 oz (910g)  (torso medium, hipbelt medium)
  • Weight Tested:  33.6 oz(953g) (torso medium, hipbelt xl)
  • Gender: Unisex
  • Torso Lengths Available: 15-17″, 17-19″, 19″-21″, 21-23″
  • Pockets: 6
  • Shoulder Straps: S-shaped
  • Frame: Plastic framesheet and center aluminum stay
  • Load Lifters: Yes
  • Hydration Compatible: Yes
  • Material: Body-Ecopak EPX200; Side pockets -Robic Extrema; Mesh – Dyneema Mesh
  • Seam-taped: No
  • Bear Canister Compatibility: BV500 and BV450 fit vertically
  • Mfg Recommended Base Weight: 22 lbs (10kg)
  • Mfg Max Recommended Load: 42 lbs (19kg)

Backpack Storage and Organization

The Mo has a standard roll top design with side water bottle pockets and a front mesh pocket.
The Mo has a standard roll-top design with side water bottle pockets and a front mesh pocket.

The Mo 50 is a standard, but stylish roll-top pack, that looks really cool in black Ecopak with orange highlights. I never thought I’d like a black backpack before, but this pack is stunning. The interior is white, however, so you can actually see what’s inside.

While the pack fabric is waterproof, the seams are not sealed, so I’d still recommend lining the inside with a plastic bag. The main compartment is hydration compatible with a hose port over each shoulder strap. There is an internal strap and hook inside to hang a reservoir, but no internal pocket to hold it in place.

The side pockets have an elastic cord tensioner w:cordlock to keep bottles from falling out.
The side pockets have an elastic cord tensioner w/cordlock to keep bottles from falling out.

The Mo has two side water bottle pockets that can fit two SmartWater bottles or two 1L Nalgene bottles side by side. The bottles are reachable when wearing the pack. The side pockets have an elastic cord/cordlock combo to secure the bottles along the top and drain holes in the bottom to remove moisture. The pockets are made with “Robic Extrema”, which is just Robic nylon with High-Density Polyethylene Fibers (HDPE) fibers running through it and is easy to patch with Tenacious Tape if you hole it.

The ends of the roll-top can be buckled to the sides of the pack with long webbing straps or together on top of the main compartment. If buckled on top, you can loop the side webbing straps around the front of the pack for added compression or to attach gear like snowshoes or a foam pad. The top of the roll-top has two plastic snaps to hold the top closed before rolling.

The top of the rolltop is held closed by snaps.
The top of the rolltop is held closed by snaps.

The Mo also has a bottom stretch pocket on the base of the pack, which has really just become a popular feature on backpacks in the past two years. Many people use it to stash a day’s worth of snacks and food, or hats and gloves, so they can be reached while you’re walking withing having to stop. One end of the pocket is completely open, while the other has a small trash hole where you can stuff candy and snack wrappers for disposal later.

I really like this bottom stretch pocket because I don’t like to take food breaks when I hike, but I’m also not very good at snacking to keep my energy up and rely on willpower instead. But I can stash quite a bit of food into this bottom pocket and pull it without stopping, which I’ve really come to appreciate the more I use the pack. Old dogs can learn new tricks.

The bottom stretch pocket is open on one side so you can reach in and pull out items without stopping.
The bottom stretch pocket is open on one side so you can reach in and pull out items without stopping.

The bottom stretch pocket is made with the same Dyneema mesh found on the front pocket, but I can’t say how long it will last if you put your pack on the ground. That’s usually the highest abrasion point on a backpack and all fabrics break down there eventually. While Dyneema fibers are strong, the Dyneema mesh is primarily nylon 6.6 which isn’t particularly abrasion resistant for this application. Ask me about it in a year or two, because I’ll probably still be using this pack then.

The front pocket is made with Dyneema Stretch Mesh.
The front pocket is made with Dyneema Stretch Mesh which is Nylon 6.6 reinforced with Dyneema fibers.

The front stretch pocket can hold 5L of items but is not included in the 50L volume of the rest of the backpack. It has enough stretch though that you can get a 1L cookpot into the pocket when the pack is packed tight. There are also seven fabric loops sewn into the seams of the front pocket which Atom has threaded with elastic cord. I’ve left it in place for illustration, but I usually remove cords like them as soon as I get a pack that has them. I hike off-trail a lot and you don’t want elastic cords hanging off a pack for that kind of thing.

Backpack Frame and Suspension

The thing that makes The Mo backpack “sing” is the frame, the hip belt, and the fact that the pack is slightly narrow (10.5″ wide by my measure) like a climbing backpack. All that makes it super comfortable to carry, with a hipbelt that doesn’t slip and a frame capable of a maximum carry of 42 lbs (says Atom Packs). I think that’s pretty close although you’ll have a hard time fitting that much heavy gear or water into or onto the pack. I’ve carried up to 33 lbs with it on long water carries and felt that I could have carried even more weight if necessary.

The internal frame is a plastic sheet with a single aluminum stay.
The internal frame is a plastic sheet with a single aluminum stay.

The Mo frame is a shaped plastic sheet with a center aluminum stay which comes pre-bent but can be bent and modified if you need something a little different. Both terminate in the center of the pack, behind a modest lumbar pad on the hip belt. Both frame components are removable, but there’s little reason to. In addition, the back of the pack behind the shoulder straps is padded with 8mm closed cell foam and covered with 500D textured nylon, which has a softshell look and feels good against your back.

The hipbelt has a modest lumbar pad.
The hipbelt has a modest lumbar pad.

The hip belt has a single center buckle with two tiers of webbing straps so you can tighten it to match the shape of your hips, enabling a customized fit for both men and women. The hip belt is 4″ wide, backed with spacer mesh, and lightly padded, with a modest lumbar pad in the back which helps keep the pack in place on the hip girdle. The hip belt is replaceable if you need a different size and is held in place by velcro behind the lumbar pad.

The hip belt has a two-tier adjustment system and does not slip. Great hip belt.
The hip belt has a two-tier adjustment system and does not slip. Great hip belt.

The Mo does not come with hip belt pockets, but Atom Packs sells them as an optional add-on. They slip over the hip belt and are held in place by front and back webbing loops. The pocket that came with my pack is made with waterproof Ecopak and has a waterproof zipper, but the ones listed for sale on the website are only made with Robic Extrema. I’d inquire if you want one with waterproof fabric.

Hip belt pockets are available but sold separately
Hip belt pockets are available but sold separately.

The shoulder straps are S-shaped, so they’ll work for men and women, curving around the sensitive bits They’re also lightly padded and backed with spacer mesh. Both straps have daisy chains sewn on the front, but they’re both covered with sewn-on and non-removable stretch mesh pockets sized for a Smartphone or snack bars. Despite this, you can still access the daisy chains under them and move the sternum strap up or down.

I wasn’t initially thrilled with these pockets, because I like adding my own accessory pockets that I move between my backpacks. But I got used to the ones on The Mo pretty quickly and found I liked them. The elastic mesh they’re made with holds onto your phone even if you bend over, but doesn’t provide any moisture protection in rain. The pockets are an option on the custom 50L Mo, so you can opt to not have them added to the pack if you’re willing to wait for a custom pack to be made.

Both of the shoulder straps have sewn on stretch mesh pockets.
Both of the shoulder straps have sewn-on stretch mesh pockets.

External Attachment Points and Compression

I’ve touched on a number of the external attachment points already including the webbing loops and elastic cord surrounding the front stretch pocket, the shoulder strap daisy chains, and hip belt attachment loops. The Mo also has a top Y strap which is good for securing a foam pad or bear canister to the top of the main compartment. There’s also an ice axe loop and a bungee cord to secure the shaft.

Orange elastic cord is threaded through loop on the side of the pack to attach extra gear.
Orange elastic cord is threaded through loops on the side of the pack to attach extra gear.

In addition to the top compression provided by the roll top’s side straps, The Mo comes with elastic cords and cord locks along the sides of the pack. But they really don’t provide any compression capability, even if they’re replaced by static cord. The cord is simply not thick enough to compress the pack. Their real function is to secure objects, like trekking poles or a Tenkara rod to the side of the pack so they don’t fall off.

You can remove the elastic cord, of course, and slide webbing straps with gatekeeper clips through the webbing loops that anchor the cords if you want more effective compression plus an attachment point. But honestly, I’ve never understood why ultralight and lightweight pack manufacturers opt to use side cords instead of webbing, when doing so removes any compression benefit.

The Mo comes with a top Y strap and load lifters.
The Mo comes with a top Y strap and load lifters.

Comparable Lightweight Backpacks


Atom Pack’s “The Mo” is available as a stock model with a set of standard features or as a custom build with your choice of colors and other options. I think the stock all-black model, reviewed here, is stunning, not just in its appearance but also functionally. The pack carries wonderfully due in large part to its unique frame and narrow dimensions, its highly adjustable hip belt and easily accessible pockets which are reachable while you’re in motion. I really can’t think of any backpack that I currently own and would rather carry than The Mo 50. It is an exceptional lightweight backpack that can hold its own with moderate loads and put a smile on your face. Highly recommended!

Disclosure: Atom packs donated a backpack for review.

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