Review: Aer City Pack Pro 2 (24L, Ultra)
Disclaimer
Aer provided me with the City Pack Pro 2 for review purposes. No money exchanged hands, but I do get to keep the bag. The opinions in this review are entirely my own; Aer does not get to see this post before it’s published. No links in this review are affiliate links.
Aer City Pack Pro 2 (24L) in Ultra. I’m 173 cm, 68 kg (5’8”, 150 lbs).
Introduction
Aer is a San Francisco–based brand founded in 2014, held in high regard in the carry community for its practical organization, tech-minimalist aesthetics, and obsession with advanced materials. The City Pack Pro 2 is the brand's flagship everyday backpack and one of the most recommended backpacks out there.
The CPP2 comes in two sizes (20L, 24L) and four fabric options: 1680D Cordura ballistic nylon, VX-42 X-Pac, ECOPAK, and Ultra400X. The version I have is the 24L in Ultra 400X — a UHMWPE composite by Challenge Sailcloth that tops the fabric lineup and, at $269 USD, tops the price list too: $50 over the base Cordura version and $20 over the X-Pac and ECOPAK options. It comes in a single colorway which I can describe as “washed black”.
I've reviewed Aer's 1680D Cordura twice, on the Aer Day Sling 4 and the Aer Travel Pack 4, and I've written a deep-dive into Ultra as a fabric. But this is my first time with an Ultra bag in hand.
Experience
It was one of those evenings that lulls you into thinking the rainy season is taking the day off. I'd left the coworking space and swung by the mall for a few groceries, laptop bag on my shoulder, in no particular hurry to get home. Then the sky went the color of a bruise, and a monsoon arrived. No umbrella. Of course, no umbrella. By the time I made it through my door I was soaked to the skin, dripping onto the floor, groceries forgotten in my hand. My first thought was the laptop. I unzipped the laptop compartment bracing for a fogged screen and a dead keyboard. It was bone dry.
This perfectly describes the experience I’ve had with this bag over the past three months. My usual loadout was Evergoods CAP2 with a bunch of tech staff, a 15" MacBook Air, a 500 ml water bottle, an umbrella (sometimes not), and smaller items like a medications pouch, tissues, wallet and sunglasses. On days when I've had fencing classes, I pack out a change of clothes and a pair of sneakers.
Aesthetics
The Ultra might "make or break" the look of the bag for you. The distinctive features of the fabric are a cross-grid pattern, a light crinkle, and a paper-like feel. You might think the crinkles give each bag a unique texture, or you might think they make the bag look like a crumpled newspaper. You might like the washed-black color and slight satin finish, or you might prefer something that looks like a "real" fabric.
Personally, the Ultra fabric it's not quite my cup of tea — I prefer the look of ballistic nylon — but I appreciate the unique character and feel it gives the bag.
Dimensions, Volume, and Weight
Per Aer's spec sheet, the 24L measures 46 cm tall, 30.5 cm wide, and 18 cm deep, for a claimed 24L of volume. On my own tape measure, with the side pockets empty, it comes to 46 cm tall, 32 cm wide, and 17 cm deep — close to spec, with the width difference likely coming down to how the empty side pockets sit. Weight is listed at 2.57 lbs (1.17 kg); on my own scale, mine comes in at 1.1 kg — close enough to spec, but feeling lighter than the number would suggest.
Organization
The CPP2 Ultra splits into a laptop compartment, the main clamshell-opening compartment, a top pocket, a front admin pocket, and a front zippered pocket — a layout that closely mirrors the Travel Pack 4. Two side pockets are cut from the same Ultra400X shell fabric rather than mesh, keeping the monochrome look consistent all the way around.
Top Pocket
The top pocket opens to 19 cm and measures 26 x 8 cm inside. Depth is hard to pin down since the material is elastic, but I'd put it around 6–9 cm.
Front Admin Pocket
The front admin pocket measures 23 x 16 cm, with meaningfully more usable volume than that thanks to pleats in the top corners. Inside: two stretchy pockets (7.5 x 11.5 cm and 13 x 11.5 cm), a 4 x 15 cm pen slot, a 20 x 20 cm zippered pocket with no soft lining but a slot for an AirTag, and a key-leash attachment loop.
Front Zippered Pocket
The opening is 23 cm at the top, tapering to 20 cm toward the bottom, with the pocket standing 25 cm tall. Pleats at the bottom add volume, but the opening itself is tight. No internal organization beyond a key-leash attachment loop.
Side Pockets
Two side pockets, one on each side. The pockets are 13 cm wide, running from 19 cm at the lowest point up to 25 cm at the highest — an asymmetric shape rather than a straight rectangle.
Laptop Compartment
Opens wide on dual zipper heads. The sleeve itself is padded and soft-lined, with a 4 cm false bottom, plus an additional sleeve/middle area at 26 x 30 cm. I've carried a 13-inch MacBook Air and a 15-inch MacBook side by side in here without issue.
Main Compartment
15 cm deep, 45 cm tall, 30 cm wide — though the top corners are rounded, so the realistically usable area is closer to 30 x 40 cm. On the back wall, a stretchy sleeve (23 x 30 cm) sits slightly raised off the bottom. On the front wall, two zippered pockets: a stretchy one up top (21 cm opening, 25 x 15 cm) and a non-stretchy one below it (23 cm opening, 24 x 20 cm, tapering to about 20 cm at the bottom). Clamshell opening, dual zipper heads.
What I can say without measuring anything: this bag self-stands like a champ. Loaded or empty, it holds its footprint on a table or floor, which sounds trivial until you're digging through it in a coffee shop and don't have to lean it against a chair leg. Combined with the top pocket, that's a genuinely winning combination — I can grab a wallet or phone from the top without unzipping the whole bag or tipping it over first.
The main compartment lays flat for packing, and the laptop compartment is suspended and padded the way I've come to expect from Aer. Organization overall is convenient — everything has an obvious place, and the front admin pocket keeps small items away from the bulkier main cavity.
One gap: there's no hidden passport-style pocket anywhere on the bag. If you're used to that on a travel-oriented pack, you'll notice its absence here.
Materials, Hardware, and Build Quality
This is the section I most wanted to get into, because Ultra400X is a genuinely different material from anything else Aer sells, and different from anything I've reviewed on this blog so far.
The short version: Ultra400X is a laminate with a woven UHMWPE-blend face — the fiber behind Dyneema and Spectra, gram for gram stronger than steel. For the full breakdown of how it's constructed and why it outperforms much heavier fabrics, read my deep-dive into Ultra. Here, I'll focus on what it's like to live with.
In hand, Ultra400X feels lighter and drier than 1680D Cordura, with none of the softness or slouch I noted on the Able Carry Daily Plus. It holds its shape. There's a very faint, papery crispness to it.
The waterproofing is baked into the fabric's laminated construction rather than a coating that can wear off.
Hardware-wise, the CPP2 Ultra is well equipped: three plush handles (one on top, one on each side), a luggage pass-through with a velcro strap to keep it flat when not in use, a sternum strap with a strap keeper, D-rings above each side pocket, and an additional D-ring on the right shoulder strap. Nothing here feels like an afterthought, and nothing has frayed, sagged, or come loose in three months.
Zippers are PU-coated YKK throughout, and the experience is inconsistent in the same way it was on the Travel Pack 4: the top pocket, admin pocket, and laptop compartment zippers are smooth, while the larger zippers on the front zippered pocket and the main compartment are not — the main compartment zipper in particular is genuinely annoying to operate. Aer does soften that with hypalon pull tabs on both the front zippered pocket and the main compartment, which make them noticeably easier to grip and pull despite the roughness underneath.
Comfort
Comfort is very good — a solid second to the Able Carry Daily Plus in my rotation. The shoulder straps are well padded, ventilated, and have good rebound; the back panel matches that build, with the same padding, ventilation, and rebound.
There is little to say about comfort and that’s a good thing. Nothing stands out in a bad way.
Pros and Cons
Pros
Ultra 400X is noticeably lighter than 1680D Cordura while holding its shape better than the softer fabrics I've handled.
Self-stands reliably, loaded or empty.
Top quick-access pocket plus the self-standing base is a genuinely useful combo for grab-and-go items.
Versatile enough to go from tech-EDC to gym-bag duty.
Top-notch water resistance built into the fabric's lamination rather than a coating that can wear off.
Excellent comfort with plush shoulder straps and great back-panel ventilation.
Roomy enough for a weekend trip yet small enough for everyday carry.
Cons
Pricey — $269 USD, a $50 premium over the base 1680D Cordura version.
The Ultra fabric's look is polarizing and might be a dealbreaker.
Zippers aren't uniformly good. The main compartment's is the worst offender, made more obvious by sitting right next to the admin pocket's smooth one.
The front zippered pocket's opening is too tight for how much volume it actually holds, which makes getting items in and out more of a fight than it should be.
No hidden passport-style pocket.
Conclusion
This is where I'd tell you it's "by far the best bag I've had." It's not. It's not the most comfortable one, that crown is still held by the Able Carry Daily Plus. It's definitely not the best looking either, I've yet to publish my review of a certain Pioneer bag that holds that title. But I'll be damned if it's not practical.
The volume works from EDC to travel, the self-standing feature is genuinely handy, the side pockets are useful, the weight is decent, comfort is there, and water resistance is top-notch. This bag checks a lot of boxes. Does that make it a good bag for you, especially considering the price tag? That's not for me to decide, but I hope this review made your decision a little easier.
