Béis The Expandable Backpack vs Waterfly Adventure Nyx Rolltop Backpack 18L
The Béis The Expandable Backpack is 13.5L and 0.76kg1.7lb; the Waterfly Adventure Nyx Rolltop Backpack 18L is 13L and 0.74kg1.6lb. The Waterfly Adventure Nyx Rolltop Backpack 18L is 0.02kg0lb lighter. The Waterfly Adventure Nyx Rolltop Backpack 18L costs $83.00999999999999 less. The Béis The Expandable Backpack fits the carry-on limit of 36 of 36 major airlines and the Waterfly Adventure Nyx Rolltop Backpack 18L fits 36; under the seat, 10 and 20 of 26.
| Spec | Béis The Expandable Backpack | Waterfly Adventure Nyx Rolltop Backpack 18L |
|---|---|---|
| Price | $118 | $34.99Best |
| Volume | 13.5L | 13L |
| Expands to | 17L | 18L |
| Weight | 0.76kg1.7lb | 0.74kg1.6lbBest |
| Carry-on compliance | 100% | 100% |
| Personal-item compliance | 38% | 77%Best |
| Dimensions | 38.1×33×12.7cm15×13×5in | 38.1×27.1×13cm15×10.5×5in |
| Laptop | 15" | sleeve, size not published |
| Bottle pockets | 1 | 2 |
| Opening | n/a | Roll-top, Roll-top main compartment with a buckle strap, plus a back zipper |
| Warranty | n/a | 10 years |
| Organizer | Yes | No |
| Shoe compartment | No | 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 | Yes |
| Load lifters | No | No |
| Shoulder strap | No | No |
| Luggage pass-through | Yes | No |
| Camera compartment | No | No |
| Bike-ready | No | No |
| Material | 100% recycled polyester body and lining, recycled faux leather trims | Water-resistant film fabric, tear-resistant polyester, polyester lining |
| Last checked | 2026-09 | 2026-10 |
Where their airline fit differs
| Airline | Limit | Béis The Expandable Backpack | Waterfly Adventure Nyx Rolltop Backpack 18L |
|---|---|---|---|
| Air France | Personal item | Too big | Fits |
| ANA (All Nippon Airways) | Personal item | Too big | Fits |
| KLM | Personal item | Too big | Fits |
| Lufthansa | Personal item | Too big | Fits |
| Norwegian Air Shuttle | Personal item | Too big | Fits |
| Ryanair | Personal item | Too big | Fits |
| SAS | Personal item | Too big | Fits |
| Turkish Airlines | Personal item | Too big | Fits |
| Vueling | Personal item | Too big | Fits |
| Wizz Air | Personal item | Too big | Fits |
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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.