Aer Gym Duffel 3 vs Knack Expandable Metro Duffel
The Aer Gym Duffel 3 is 24.1L and 1.32kg2.9lb; the Knack Expandable Metro Duffel is 26L and 1.36kg3lb. The Aer Gym Duffel 3 is 0.04kg0.1lb lighter. The Knack Expandable Metro Duffel costs $24 less. The Aer Gym Duffel 3 fits the carry-on limit of 31 of 36 major airlines and the Knack Expandable Metro Duffel fits 31; under the seat, 0 and 0 of 26.
| Spec | Aer Gym Duffel 3 | Knack Expandable Metro Duffel |
|---|---|---|
| Price | $169 | $145Best |
| Volume | 24.1L | 26L |
| Expands to | n/a | 36L |
| Weight | 1.32kg2.9lbBest | 1.36kg3lb |
| Carry-on compliance | 86% | 86% |
| Personal-item compliance | 0% | 0% |
| Dimensions | 29×43×23cm11.5×17×9in | 33×43.2×22.9cm13×17×9in |
| Laptop | 16" | 16" |
| Bottle pockets | 2 | 1 |
| Opening | Zippered main compartment | zip top |
| Warranty | Lifetime | n/a |
| Organizer | Yes | Yes |
| Shoe compartment | Yes | No |
| Hydration sleeve | No | No |
| Frame sheet | No | No |
| Water-resistant | No | Yes |
| Rain cover | No | No |
| MOLLE | No | No |
| Hip belt | No | No |
| Sternum strap | No | No |
| Load lifters | No | No |
| Shoulder strap | Yes | Removable |
| Luggage pass-through | Yes | Yes |
| Camera compartment | No | No |
| Material | 1680D CORDURA ballistic nylon exterior, antimicrobial-treated liner, YKK zippers, Duraflex hardware | Water-resistant 900 x 1200 denier high-twist high-density polyester, 150D antimicrobial nylon lining |
| Last checked | 2026-09 | 2026-09 |
Where their airline fit differs
Both bags pass and fail the same airline size limits.
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Specs come from each brand's own product page. Fit uses listed dimensions in any orientation. How we score carry-on fit.