Hyperlite Mountain Gear Unbound 40 vs Zpacks Arc Haul Ultra 60
vs
Quick take: The Zpacks Arc Haul Ultra 60 costs $6 less; the Zpacks Arc Haul Ultra 60 carries more (60 vs 40 liters); the Zpacks Arc Haul Ultra 60 is lighter (1.32 vs 2.16 lbs).
| Spec | Hyperlite Mountain Gear Unbound 40 | Zpacks Arc Haul Ultra 60 |
|---|---|---|
| Price | $405 | $399 |
| Rating | 4.8★ (4) | — |
| Type | Ultralight Pack | Ultralight Pack |
| Frame Type | Internal Frame | Internal Frame |
| Capacity | 40 L | 60 L |
| Weight | 2.16 lbs | 1.32 lbs |
| Max Load | 30 lbs | 40 lbs |
| Torso Fit | Sized S-L, 15-21 in | User-adjustable frame height |
| Material | 150D DCH fabric with Dyneema stretch mesh | Ultra 100X body with nylon mesh pockets |
| Back Panel | Removable aluminium stay with embedded foam | Curved carbon fibre stays with tensioned arc |
| Adjustable torso | No | Yes |
| Ventilated back | No | Yes |
| Raincover included | No | No |
| Hipbelt pockets | Yes | Yes |
| Removable lid | No | No |
| Hydration sleeve | Yes | No |
| Fits BV500 bear can | No | Yes |
| Warranty | HMG limited lifetime on defects | Zpacks 2-year on materials and workmanship |
Pros & cons
Hyperlite Mountain Gear Unbound 40
- ✓The bottom stash pocket — grab a layer or snacks without stopping — is the feature owners say they can't go back from.
- ✓Waterproof Dyneema construction means no pack liner and no wet-gear anxiety.
- ✓At 1.72 lbs with removable stays it competes with frameless packs while carrying meaningfully better.
- ✓The stretch front pocket (unlike the Southwest's solid one) swallows a soaked tent for on-the-move drying.
- ✓Made-in-Maine build quality matches its flagship siblings.
- ✓The 40L discipline forces a genuinely light kit, which converts say improved their whole system.
- ✓Clean compression lets it double as a big daypack or peak-bagging bag.
- ✓The white-and-black aesthetic carries the same HMG cachet.
- ✗40 liters plus no bear-canister fit rules out canister country and long food carries — a hard constraint, not a preference.
- ✗$349 for less volume than a $199 Flash 55 makes the per-liter math painful.
- ✗The 30 lb ceiling is firm; winter or water-heavy trips overwhelm it.
- ✗Same clammy foam-on-back feel as every HMG.
- ✗Fixed sizes, minimal try-on options, and a boxy fit — the standard HMG sizing gamble.
- ✗The stretch pocket wears faster than the Southwest's solid fabric in brush.
- ✗Hipbelt pockets remain small for big phones.
- ✗It assumes an already-dialed kit; beginners who buy the aesthetic first find it unforgiving.
Zpacks Arc Haul Ultra 60
- ✓The lightest framed, ventilated 60L pack money can buy — nothing else combines 21.7 oz with a real airflow gap.
- ✓Backpacker magazine's best ultralight pack of 2026, adding mainstream validation to years of thru-hiker use.
- ✓The tensioned arc genuinely works: sweat reports drop dramatically versus foam-back cottage rivals.
- ✓Ultra 100X fabric is waterproof and far more abrasion-resistant than the old DCF packs.
- ✓The user-adjustable frame height effectively customizes torso length — rare in the cottage world.
- ✓Carries 35-40 lbs shockingly well for its weight, per repeated long-trail reviews.
- ✓Modular add-on ecosystem (belt pouches, shoulder pockets, lumbar pads) lets owners spec it like a custom pack.
- ✓Zpacks' repair department keeps long-trail packs alive mid-hike with fast turnarounds.
- ✗Early Ultra-fabric generations had documented delamination reports; Zpacks revised the laminate, but the history follows the brand on Reddit.
- ✗$399 plus the add-ons most people want pushes real cost toward $475.
- ✗The arc frame takes fiddling to tension right, and a mis-set arc pokes the lumbar.
- ✗The 2-year warranty is thin next to ULA's and Osprey's lifetime coverage.
- ✗The curved frame reduces usable volume and makes tall canisters ride oddly.
- ✗No hydration sleeve — bottle-only hydration is assumed.
- ✗Mesh and edge trim wear faster than the body fabric; brush country is not its habitat.
- ✗The whole design rewards careful owners and punishes casual abuse — it's precision gear, not a rental mule.