Bookers, this is the written companion to my full video review. If you’d rather watch me drag this bag through three airports and then put my laptop inside it during a downpour, here you go.

TL;DR

I bought the AER Travel Pack 4 35L in Cordura, paid $345 for it in Japan (it retails for $259 in the US), and ran it through three flights across three countries over six weeks of real travel. The simplifications from the V3 are smart, the new luggage pass-through is the only change that’s an upgrade and not an argument, and yes, it’s still a heavy pack. If you want a clean, structured, will-last-a-decade carry-on and you’re not flying Ryanair every week, this is a buy. If you want the lightest 35L on the market, look at the Cotopaxi Allpa.

What I’m Actually Carrying

I own the 35L in 1680D Cordura ballistic nylon. AER also makes the V4 in X-Pac VX-42 and Challenge Ultra400X, and both come in a 28L size. I haven’t tested those personally, so the firsthand verdict in this post is for the 35L Cordura only. The buying guide tables further down cover the full lineup if you’re trying to figure out which variant to get.

Full lineup specs

Part 1: Did I Get Ripped Off?

Yes. I paid $345 for this bag at a shop in Japan. It retails for $259 in the United States. So I ate roughly $86 in Japan tax just so I could start using it on the trip instead of waiting until we got back. Feel free to roast me in the comments.

Here’s the thing. We do a lot of slow travel with Allie and the kids. Six weeks ago when I picked this up, we had a 15-hour flight ahead of us and three more flights after that. I wasn’t going to wait. If you have time and you’re shopping in the US, save the $86. If you’re already abroad and the bag is in front of you, the math is different.

That price difference also tells you something about the brand. AER bags don’t get heavily discounted internationally. They hold value. The boxy structure, the 1680D ballistic nylon, the YKK and Duraflex hardware: this is a pack people buy once and use for a decade. The international markup is what it is because the bag is what it is.

Part 2: What Actually Changed from the Travel Pack 3 to the Travel Pack 4

Five visible changes. Some are upgrades, some are arguments, one is genuinely an upgrade that nobody should argue about. Here’s the full table, then I’ll walk through each one with my take from six weeks of use.

The admin panel got smaller, and that’s good

The V3 had a massive admin panel: pen slots, card slots, dedicated organization spots for everything. People are mad it’s gone. I’m not. The V4 still has a zipper pocket, a grab and stash pocket, two stretch organization pockets, and a deep pocket where I keep my AirFly Bluetooth dongle for plane audio. That’s enough.

Allan, the founder, said this is becoming more of a dump pocket. After six weeks of using it, I agree. I don’t need three pen slots. I need a place to stuff my passport, my Bluetooth dongle, and a few cards when I’m moving through an airport. The V4 does that, and it leaves more interior volume for actual packing.

The water bottle pocket finally makes sense

The V3’s water bottle pocket was overengineered. Cordura nylon, a zipper, the works. The V4 is just simple stretch material. It fits a sparkling water bottle from a European grocery store with zero fight. That’s the test. If your water bottle pocket requires a zipper, it’s not actually a water bottle pocket.

The compression straps are gone (RIP)

I liked the V3 compression straps. Allan didn’t. He said he was watching travelers in airports and nobody was using them. They were just dangling. Word origin sidebar: “dangle” entered English in the 1500s and has always meant something hanging there doing nothing. Did Allan see your straps dangling, Booker? Because I don’t dangle.

That said, after six weeks without them, I miss them maybe twice. If you pack to capacity (which most one-bag travelers do), compression straps don’t do much. If you regularly travel underpacked and want to cinch the bag down, this is a real downgrade for you. For me, the answer is to just pack the bag full or use a packing cube to compress my clothes instead.

The luggage pass-through is an upgrade, not an argument

The V3’s luggage pass-through was horizontal. The V4’s is vertical. When you slide it over the handle of a roller bag, the pack now stands upright instead of tipping. That’s the entire change and it’s just better. There is no version of this where someone preferred horizontal.

The shape is rounder

The V3 was boxy and tactical. The V4 is rounder and sleeker. The internet is calling the V4 a bigger City Pack Pro 2. In an interview, Allan basically admitted that: he said the V4 is a bigger City Pack Pro 2 with travel details built inside. So if your argument is that they made the City Pack Pro 2 bigger, the founder agrees with you. If you want the boxy V3 aesthetic, just buy the V3 (or hold out for the inevitable reseller market).

What I Actually Packed In It

For the trip I tested this on, here’s what went inside:

• One Muji medium packing cube (5 to 7 days of clothes)
• One smaller Epica compression packing cube (extra clothes, compressed)
• TomToc tech organizer for cables, dongles, batteries
• 16-inch laptop in the rear sleeve
• 20,000 mAh power bank in the top internal pocket
• Sequins travel journal (the durable one, I write in it every morning)
• Two Muji pouches (cash, stain wipes, miscellaneous small stuff)
• Folding flat sunglasses case (lives in the top stretch pocket)
• AirFly Bluetooth dongle (in the front admin)

That setup left me with enough room to add a packable rain layer and a paperback. The 35L is enough for a family slow travel rotation if you do laundry every five to seven days. If you don’t do laundry mid-trip, you’re going to feel cramped at the two-week mark.

The Rain Test (With My Laptop Inside)

It started raining on the day I was filming. I made a decision that in retrospect was either a good content choice or a terrible life choice, depending on how it ended: I put my laptop in the rear sleeve and kept filming in the rain. I wanted to genuinely test the AquaGuard zipper on the laptop compartment.

Result: the zipper got wet. The laptop stayed dry. That is exactly what the AquaGuard zipper is supposed to do. I’m not going to start writing reviews from a soaking wet MacBook, so we passed.

For the record: the rest of the pack uses regular YKK zippers, not AquaGuard. AER only put the AquaGuard treatment on the main laptop compartment. If you’re caught in a downpour without a rain cover, your laptop is the safest item in the bag. Everything else depends on how thoroughly you got soaked.

The Material Question: Cordura, X-Pac, or Ultra400X

I own the Cordura. I haven’t tested the X-Pac or Ultra editions personally, so this is materials analysis, not field testing. The three fabrics behave differently and that affects which one is right for you.

1680D Cordura ballistic nylon is what I bought. It’s heavy (1.78 kg empty for the 35L), abrasion-resistant to a degree that’s overkill for most travel, and water-resistant but not waterproof. It’s the same fabric class you find on military and law enforcement gear. Pick this if you want a pack that will look the same after ten years of abuse.

X-Pac VX-42 is a laminated sandwich (face fabric, polyester cross-ply, waterproof film, backing). It’s fully waterproof at the fabric level, lighter than Cordura, and slightly less abrasion-resistant. It crinkles when handled. Pick this if you want waterproof and lighter.

Challenge Ultra400X is UHMWPE (Dyneema-family) ripstop laminated to a waterproof film. It’s the lightest of the three, the most tear-resistant, and the most weather-resistant. Lower abrasion ceiling than ballistic nylon. Pick this if you need every gram saved and you can stomach the premium price.

Price across the lineup

Is It Carry-On Compliant?

My 35L Cordura cleared overhead bins on three flights with three different carriers without a second look. But the published numbers tell a more nuanced story. The 35L is right at the US carry-on ceiling, and it fails Ryanair and EasyJet on at least one dimension.

If you fly European budget carriers regularly, the 28L is the safer pick. If you fly US legacy carriers and full-service international, the 35L is fine.

How It Compares to the Category

vs. Peak Design Travel Backpack 45L: The Peak Design expands from 30L to 45L and includes a hip belt. The AER doesn’t expand and the hip belt is sold separately. Cordura is more abrasion-resistant than Peak Design’s 400D recycled nylon canvas, but the Peak Design is more versatile if you want one bag that scales from day trip to two-week trip.

vs. Tortuga Travel Backpack Pro 40L: The Tortuga has an integrated weight-bearing hip belt that transfers 80% of the load off your shoulders. If you walk long distances with a fully packed bag, that’s a real functional advantage. The AER is more structured and has the more durable fabric, but the Tortuga is the better choice if you’re going to be on your feet a lot.

vs. Cotopaxi Allpa 35L: The Cotopaxi is 450 grams lighter (1.33 kg vs 1.78 kg) and $29 cheaper. The AER has more durable fabric and better structure. If weight is your priority and you don’t mind the more casual Cotopaxi aesthetic, the Allpa wins on the spec sheet. The AER wins on long-term build quality.

Part 3: Peeps Mad on the Internet

Two recurring complaints worth addressing.

“It’s just a bigger City Pack Pro 2”

The founder agrees with you. In an interview Allan said the V4 is essentially a bigger City Pack Pro 2 with travel features added. So this isn’t a gotcha. If you want the boxy tactical V3 aesthetic, buy the V3 while it’s still in stock. If you like the City Pack Pro 2 silhouette scaled up for travel, the V4 is exactly what was advertised.

“It’s too heavy”

It is. 1.78 kg empty for the 35L Cordura is heavy. That’s because it’s 1680D Cordura ballistic nylon, which is one of the most abrasion-resistant fabrics in the category. You can’t have indestructible fabric and lightweight construction. Physics doesn’t allow it. If weight matters more than durability, get the Ultra400X edition ($309), the Cotopaxi Allpa 35L (1.33 kg, $230), or a different category of pack entirely. The AER 35L Cordura is a ten-year pack, not a featherweight pack.

Part 4: The Final Verdict

After six weeks of real use, three flights, three countries, and one ill-advised rain test:

Buy the 35L Cordura ($259) if you slow travel, you don’t fly Ryanair every week, and you want a bag that will outlast the laptop you carry in it. This is what I bought and what I’d buy again.

Buy the 28L Cordura ($239) if you fly European budget carriers, you do laundry weekly, or you travel for three to five day stretches at a time.

Buy the 35L Ultra400X ($309) if you specifically need the lightest possible structured carry-on and you’re already paying premium baggage fees that the $50 will offset within a year.

Skip it if you need an integrated hip belt (get the Tortuga Travel Backpack Pro 40L), you need compression range (get the Peak Design Travel Backpack 45L), or you want the lightest 35L for the lowest price (get the Cotopaxi Allpa 35L).

Personal take: I don’t regret the $345 I paid in Japan. I would have regretted waiting six weeks to start using it more.

FAQ

Is the AER Travel Pack 4 worth the price?

For the 35L Cordura at $259 in the US, yes, if you want a durable, structured one-bag travel pack and you’re willing to carry the weight. If $230 Cotopaxi Allpa 35L weight savings matter more to you, no.

What’s the difference between the Travel Pack 3 and Travel Pack 4?

Five changes: simpler admin panel, simpler water bottle pocket, no compression straps, vertical luggage pass-through, and a rounder less boxy shape. The new pass-through is a clear upgrade. The rest are tradeoffs.

Should I get the 28L or 35L?

28L for three to five day trips and stricter airline compliance. 35L for one to two week trips and slow travel. I own the 35L because we do extended trips with the family.

Does the Travel Pack 4 have a hip belt?

No. AER sells a Cordura hip belt as a separate accessory. The pack has attachment points for it but it’s not included.

Is the AER Travel Pack 4 waterproof?

The laptop compartment has a YKK AquaGuard zipper and survived my rain test. The rest of the pack uses standard YKK zippers and is water-resistant but not waterproof. The X-Pac and Ultra400X fabric editions are waterproof at the fabric level, but you’d still want a rain cover in a real downpour.

Does it fit a 16-inch laptop?

Yes. Both sizes have a padded, suspended laptop sleeve that fits up to 16 inches. Mine survives the AquaGuard zipper rain test (which is more than I can say for my decision-making that day).

Should I buy Cordura, X-Pac, or Ultra400X?

Cordura for durability and budget (what I have). X-Pac for waterproofing and balanced weight. Ultra400X if you need every gram saved and you’ll pay the $50 premium for it.

How heavy is it fully packed?

The 35L Cordura is 1.78 kg empty. Mine packs out to roughly 9 to 10 kg with a 16-inch laptop, clothes for slow travel, tech, and accessories. Without a hip belt, all of that rides on your shoulders.

What’s the warranty?

AER offers a limited lifetime warranty against manufacturing defects.

Why is the AER Travel Pack 4 so much more expensive in Japan?

Japan tax. I paid $345 for a $259 bag because I wanted to start using it on the trip. If you have time and you’re shopping in the US, save the money.

Final Note

If you watched the full video, thank you. If you came here from a Google search instead, the video’s at the top of this post. Watch the rain test. Watch the through-the-tire shot. And let me know in the YouTube comments if you’d make the same Japan tax decision I did or if you’d have waited.