Dakine 365 Backpack 21L vs Waterfly TransformerX Ultralight Packable Backpack 20L
The Dakine 365 Backpack 21L is 21L and 0.31kg0.7lb; the Waterfly TransformerX Ultralight Packable Backpack 20L is 20L and 0.29kg0.6lb. The Waterfly TransformerX Ultralight Packable Backpack 20L is 0.02kg0lb lighter. The Waterfly TransformerX Ultralight Packable Backpack 20L costs $32.010000000000005 less. The Dakine 365 Backpack 21L fits the carry-on limit of 32 of 36 major airlines and the Waterfly TransformerX Ultralight Packable Backpack 20L fits 36; under the seat, 0 and 9 of 26.
| Spec | Dakine 365 Backpack 21L | Waterfly TransformerX Ultralight Packable Backpack 20L |
|---|---|---|
| Price | $58 | $25.99Best |
| Volume | 21L | 20L |
| Weight | 0.31kg0.7lb | 0.29kg0.6lbBest |
| Carry-on compliance | 89% | 100%Best |
| Personal-item compliance | 0% | 35%Best |
| Dimensions | 45×31×21cm17.5×12×8.5in | 42.9×29×14cm17×11.5×5.5in |
| Laptop | 15" | n/a |
| Bottle pockets | n/a | 2 |
| Opening | n/a | Zippered main compartment |
| Warranty | 10 years | 10 years |
| Organizer | No | 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 | No | No |
| Camera compartment | No | No |
| Bike-ready | No | No |
| Material | 89% recycled polyester, 11% nylon body; polyester lining | Tear-resistant, water-resistant nylon, polyester lining |
| Last checked | 2026-09 | 2026-10 |
Where their airline fit differs
| Airline | Limit | Dakine 365 Backpack 21L | Waterfly TransformerX Ultralight Packable Backpack 20L |
|---|---|---|---|
| Air Arabia | Carry-on | Too big | Fits |
| Air Canada | Personal item | Too big | Fits |
| Air India | Carry-on | Too big | Fits |
| Allegiant Air | Personal item | Too big | Fits |
| American Airlines | Personal item | Too big | Fits |
| British Airways | Personal item | Too big | Fits |
| easyJet | Personal item | Too big | Fits |
| Frontier Airlines | Personal item | Too big | Fits |
| JetBlue Airways | Personal item | Too big | Fits |
| LATAM Airlines | Personal item | Too big | Fits |
| Ryanair | Carry-on | Too big | Fits |
| Volaris | Personal item | Too big | Fits |
| Vueling | Carry-on | 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.