---
url: "https://onebag.travel/compare/2rbg4dtslw/aer-travel-pack-4-35l/ayd517mvmi/alpha-one-niner-sert-penumbra-2-0-backpack/"
title: "Aer Travel Pack 4 35L vs Alpha One-Niner SERT, PENUMBRA 2.0 Backpack"
description: "Aer Travel Pack 4 35L vs Alpha One-Niner SERT, PENUMBRA 2.0 Backpack: capacity, weight, dimensions and how many airlines accept each as a carry-on, side by…"
source: "https://onebag.travel/compare/2rbg4dtslw/aer-travel-pack-4-35l/ayd517mvmi/alpha-one-niner-sert-penumbra-2-0-backpack/"
---
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2.  [Carry-On Travel Backpacks](https://onebag.travel/carryons/)
3.  Aer Travel Pack 4 35L vs. Alpha One-Niner SERT, PENUMBRA 2.0 Backpack

# Aer Travel Pack 4 35L vs. Alpha One-Niner SERT, PENUMBRA 2.0 Backpack

Two carry-on travel backpacks, compared spec for spec.

## [Aer Travel Pack 4 35L](https://onebag.travel/carryon/2rbg4dtslw/aer-travel-pack-4-35l/)

by [Aer](https://onebag.travel/carryons/?brands=Aer)

![Front facing view of the Aer Travel Pack 4 35L](https://res.cloudinary.com/obt/image/upload/c_fill,w_400/v1788990469/carryons/aer-travel-pack-4-35l-2rbg4dtslw.webp)

<table class="table table-sm cmp-spec mt-2"><tbody><tr><td>Capacity</td><td>35 L</td></tr><tr><td>Weight</td><td>1.8 kg</td></tr><tr><td>Dimensions</td><td>55×34×23 cm</td></tr><tr><td>Airline fit</td><td>68%</td></tr><tr><td>Price</td><td>$260</td></tr></tbody></table>

## Feature by feature

| Aer Travel Pack 4 35L | Feature | Alpha One-Niner SERT, PENUMBRA 2.0 Backpack |
| --- | --- | --- |
| Storage |
| N | Compression | 2 |
| None | Expanded Capacity | None |
| 1 | Opening | 1 |
| top | Passport | front |
| Y | Passthrough | Y |
| Carry |
| Y | Backpack | Y |
| optional | Hip Belt | optional |
| removable | Sternum Strap | removable |
| Inside |
| 16in | Laptop | 16in |
| 5 | Main Compartments | 5 |
| Y | Organizer | Y |
| Outside |
| × | Hard Shell | × |
| N | Rain-fly | N |
| 2, side | Water Bottle Holder | 2, side |
| Y | Water Resistant | Y |

<table class="cmp-material"><tbody><tr><td colspan="2">Material</td></tr><tr><td>1680D CORDURA® ballistic nylon exterior (bluesign® approved)</td><td>Available in: X-Pac X42, 500D, 630D HD</td></tr></tbody></table>

## [Alpha One-Niner SERT, PENUMBRA 2.0 Backpack](https://onebag.travel/carryon/ayd517mvmi/alpha-one-niner-sert-penumbra-2-0-backpack/)

by [Alpha One-Niner](https://onebag.travel/carryons/?brands=Alpha One-Niner)

![Front facing view of the Alpha One-Niner SERT, PENUMBRA 2.0 Backpack](https://res.cloudinary.com/obt/image/upload/c_fill,w_400/v1788990332/carryons/alpha-one-niner-sert-penumbra-2-0-backpack-ayd517mvmi.webp)

<table class="table table-sm cmp-spec mt-2"><tbody><tr><td>Capacity</td><td>21 L</td></tr><tr><td>Weight</td><td>1.5 kg</td></tr><tr><td>Dimensions</td><td>47×30×14 cm</td></tr><tr><td>Airline fit</td><td>93%</td></tr><tr><td>Price</td><td>$255</td></tr></tbody></table>

## Key differences between the Aer Travel Pack 4 35L and Alpha One-Niner SERT, PENUMBRA 2.0 Backpack

-   **Compression straps:** No on the Aer Travel Pack 4 35L; 2 on the Alpha One-Niner SERT, PENUMBRA 2.0 Backpack.
-   **Passport pocket:** Top on the Aer Travel Pack 4 35L; Front on the Alpha One-Niner SERT, PENUMBRA 2.0 Backpack.

Both have: luggage passthrough, backpack straps, hip belt, sternum strap, laptop sleeve, built-in organizer, water bottle pockets, water resistant.

## Which airlines take each bag as a carry-on

We checked both bags against the carry-on size limits of 189 airlines. 129 accept both. 0 accept only the Aer Travel Pack 4 35L, and 46 accept only the Alpha One-Niner SERT, PENUMBRA 2.0 Backpack.

### Only the Alpha One-Niner SERT, PENUMBRA 2.0 Backpack fits

Air Baltic, Air China, Air Malta, Air Niugini, Air Serbia, Air Seychelles, Asiana Airlines, ATA Airlines, Belavia, Blue Air, Bulgaria Air, China Eastern, Emirates Airlines, Enter Air, Etihad Airways, flybe, Icelandair, InselAir, Juneyao Airlines, Liat Airlines, Luxair, Meridiana Fly, Nordwind Airlines, Oman Air, Pakistan International, Qatar Airways, Regional Express, Royal Brunei Airlines, Royal Jordanian, Ryanair, S7, Scoot, Shandong Airlines, Shenzhen Airlines, Sun Express, TAP Air Portugal, TAROM, Tianjin Airlines (A320 & E190), Tiger Airways, TUI, Ukraine International, VIM Airlines (Closed), Virgin Australia, Volotea, WestJet, Xiamen.

## Aer Travel Pack 4 35L vs. Alpha One-Niner SERT, PENUMBRA 2.0 Backpack: which should you pack?

The **Aer Travel Pack 4 35L** carries 14L more than the **Alpha One-Niner SERT, PENUMBRA 2.0 Backpack** (35L vs. 21L), while the **Alpha One-Niner SERT, PENUMBRA 2.0 Backpack** is the lighter pack at 1.5kg (vs. 1.8kg). For carry-on flexibility, the **Alpha One-Niner SERT, PENUMBRA 2.0 Backpack** fits 93% of the airlines we track — the higher of the two. If you prioritise packing volume, choose the Aer Travel Pack 4 35L; if you want to travel lighter, the Alpha One-Niner SERT, PENUMBRA 2.0 Backpack is the better call.