Side-by-side comparison based on expert reviews and community consensus.
Hyperlite Mountain Gear Southwest 55
Best UltralightREI Co-op Flash 55
Best ValuePrice
$349-$399
$199-$229
Summary
Sub-2-pound Dyneema construction is fully waterproof, tear-resistant, and rated to carry 40 lbs — a combination no other ultralight pack matches. The go-to choice for serious thru-hikers on the PCT, AT, and beyond.
At $199, the Flash 55 punches well above its price with a steel internal frame, adjustable torso, and fully removable components that let you strip weight as needed. It's the go-to recommendation for budget-conscious backpackers and thru-hikers alike.
Pros
- Under 2 lbs (1 lb 13.7 oz) with Dyneema fabric that's fully waterproof and tear-resistant
- Rated to carry loads up to 40 lbs — far more than most ultralight packs (typically 30-35 lbs)
- Removable aluminum stays, foam back panel, and wide supportive hip belt for load transfer
- Available in 40L, 55L, and 70L capacities
- Excellent value at $199 with steel internal frame and padded mesh hip belt
- Fully adjustable torso length; comes in four sizes including large torso/small hip combo
- Removable lid, hip belt, compression straps, and pockets allow 7 oz weight savings
- Tested extensively in demanding conditions including Wyoming's Wind River Range
Cons
- Expensive at $399 — nearly twice the cost of the REI Flash 55
- Minimal organization: lidless design with streamlined storage may shock traditional backpackers
- Dyneema back panel offers poor ventilation — gets sweaty in hot climates
- Thin 100D nylon body lacks durability of pricier packs; 210D only on the bottom
- Padded back panel doesn't offer the ventilation of suspended mesh designs
- Removable shoulder pocket prone to catching and falling off; barely fits large phones
Our take
If you're logging serious miles and want the lightest pack that won't fall apart, the Southwest 55 is the answer. It's expensive and minimal, but Dyneema's strength-to-weight ratio is in a class of its own.
The Flash 55 is borderline perfect for the price. Adjustable torso, removable lid and hip belt, and a frame that handles 30+ lbs — you'd pay $100 more for marginally better materials elsewhere.
Buy
