Gossamer Gear G4-20 Ultralight 42 Backpack vs Zpacks Arc Haul Ultra 40L
The Gossamer Gear G4-20 Ultralight 42 Backpack is 42L and 0.7kg1.5lb; the Zpacks Arc Haul Ultra 40L is 40L and 0.62kg1.4lb. The Zpacks Arc Haul Ultra 40L is 0.08kg0.2lb lighter. The Gossamer Gear G4-20 Ultralight 42 Backpack costs $194 less. The Gossamer Gear G4-20 Ultralight 42 Backpack fits the carry-on limit of 3 of 36 major airlines and the Zpacks Arc Haul Ultra 40L fits 0; under the seat, 0 and 0 of 26.
| Spec | Gossamer Gear G4-20 Ultralight 42 Backpack | Zpacks Arc Haul Ultra 40L |
|---|---|---|
| Price | $205Best | $399 |
| Volume | 42L | 40L |
| Weight | 0.7kg1.5lb | 0.62kg1.4lbBest |
| Carry-on compliance | 8%Best | 0% |
| Personal-item compliance | 0% | 0% |
| Dimensions | 59.9×29×11.9cm23.5×11.5×4.5in | 74×31.8×12.75cm29×12.5×5in |
| Laptop | no laptop sleeve | no laptop sleeve |
| Compartments | 1 | 1 |
| Bottle pockets | n/a | 2 |
| Opening | Roll-top, Extendable roll top with dual closure options | Roll-top, Roll top closure |
| Warranty | 1 year | 2 years |
| Torso length | 29.2 to 59.7cm (11.5 to 23.5in) | 40.6 to 66cm (16 to 26in) |
| Sizes | Small, Medium, Large | Short, Medium, Tall |
| Organizer | No | No |
| Shoe compartment | No | No |
| Hydration sleeve | No | Yes |
| Frame sheet | No | Yes |
| Water-resistant | No | Yes |
| Rain cover | No | No |
| MOLLE | No | No |
| Hip belt | Yes | Yes |
| Sternum strap | No | Yes |
| Load lifters | No | Yes |
| Shoulder strap | No | No |
| Luggage pass-through | No | No |
| Camera compartment | No | No |
| Bike-ready | No | No |
| Material | 70D and 100D recycled Robic nylon, PFAS free | Ultra 100X (3.3 oz/sqyd) with waterproof backing, stretch mesh pockets, taped seams, PFAS free |
| Last checked | 2026-09 | 2026-09 |
Where their airline fit differs
| Airline | Limit | Gossamer Gear G4-20 Ultralight 42 Backpack | Zpacks Arc Haul Ultra 40L |
|---|---|---|---|
| Frontier Airlines | Carry-on | Fits | Too big |
| Singapore Airlines | Carry-on | Fits | Too big |
| Southwest Airlines | Carry-on | Fits | Too big |
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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.