#2 on this list
Unbound 40
Hyperlite Mountain Gear
The Hyperlite Mountain Gear Unbound 40 is engineered directly for dedicated thru-hikers with dialed kits who prefer external gear access on the move. Where the Southwest line favors impenetrable armor, the Unbound adjusts Hyperlite's platform to meet modern trail habits, providing flexible storage options for fast-paced days. The main body uses a proven Dyneema Composite Hybrid fabric, keeping your sleeping bag and clothing insulated from rain. Load transfer is managed by a single removable aluminum stay that works alongside an internal frame sheet. What separates the Unbound from its siblings is the exterior storage: a large front stretch mesh pocket provides a ventilated spot for drying wet rain gear, while an integrated bottom mesh pocket lets you stash snacks and wrappers without taking off the pack. With 40 liters of internal volume, this pack demands disciplined gear selection. Hikers carrying synthetic insulation, bulky four-season gear, or full-size bear canisters will find the space tight. Furthermore, the external stretch mesh, while convenient, is noticeably more fragile than the hardline pockets of the Southwest. The back panel also shares Hyperlite's flat design, trapping body heat on muggy climbs. **Highlights** - Dual-direction bottom mesh pocket enables snack and trash storage without stopping. - Water-resistant Dyneema Composite Hybrid fabric keeps internal gear dry. - Front stretch mesh pocket provides easy gear stowing and air-drying. - Removable hipbelt adds versatility for trips requiring minimal weight. - 40-liter internal volume encourages disciplined, ultralight kit packing. **Watch-outs** - High price tag near $385 for a 40-liter pack. - Limited capacity struggles with rigid bear canisters or bulky cold-weather gear. - Back panel lacks ventilation channels.
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#3 on this list
Circuit
ULA Equipment
The ULA Equipment Circuit is a legendary workhorse that bridges the gap between delicate ultralight sacks and traditional backpacking haulers. It suits long-distance hikers who carry heavier base weights, tackle extended waterless stretches, or frequently hike through areas requiring a bear canister. The Circuit's strength lies in its suspension. It combines a carbon fiber and fiberglass loop frame with a central aluminum stay, funneling weight cleanly to the hips and comfortably supporting loads up to 35 pounds. The pack body is sewn from tough 400D Robic nylon, providing substantial puncture resistance that withstands years of trail abuse. ULA also offers extensive fit customization, including multiple torso lengths, separate hipbelt sizes, and both J-shaped and contoured S-shaped shoulder straps to fit diverse body types. At roughly 2 pounds 6.5 ounces, the Circuit is heavier than minimalist sub-two-pound competitors. Robic nylon is tough and treated with water-resistant coatings, but it is not waterproof; you will still need a trash bag liner or pack cover in sustained rainfall. The roll-top and top strap arrangement is functional, but the pack lacks the sleek, modern styling found on newer technical offerings. **Highlights** - Hybrid carbon fiber loop and aluminum stay carry up to 35 pounds reliably. - Tough 400D Robic nylon fabric offers high tear and scuff resistance. - Extensive sizing options including distinct torso sizes and S-curve harness options. - Massive hipbelt pockets easily fit modern smartphones and multiple snacks. - Interior volume easily fits full-sized bear canisters horizontally or vertically. **Watch-outs** - Heavier than minimalist composite-fabric packs. - Requires an internal pack liner during sustained storms. - Aesthetic and design feel utilitarian compared to modern race-inspired packs.
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- $450 MSRP
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Specs side by side
| Spec | Unbound 40 | Circuit |
|---|---|---|
| Base Weight | 1 lb. 13.6 oz. (size medium) | 2 lb 6.5 oz (1,090 g) |
| Internal Capacity | 40 liters | — |
| Primary Material | Dyneema Composite Hybrid 3.8 | 400D Robic nylon |
| Frame System | Single aluminum stay with internal frame sheet | — |
| Closure Style | Roll-top with side and top compression | — |
| Retail Price | Approximately $385 | — |
| Frame Structure | — | Carbon fiber loop with aluminum stay |
| Load Rating | — | Up to 35 lb (16 kg) |
| Shoulder Harness | — | Contoured S-straps or standard J-straps |
| Approximate Price | — | $300 |
What our reviewers liked and didn't
Unbound 40
- Dual-entry bottom pocket allows on-the-move snacking without removing the pack.
- Fully taped Dyneema Composite Hybrid body provides outstanding weather resistance.
- External stretch mesh offers ventilated drying for damp shelters and layers.
- Removable stay and hipbelt allow customizable weight reduction for lighter trips.
- Steep retail price of approximately $385 presents a high barrier to entry.
- Flat back panel lacks airflow channels, causing noticeable sweat accumulation.
- External stretch mesh is vulnerable to snagging during off-trail bushwhacking.
Circuit
- Handles loads up to 35 pounds cleanly thanks to hybrid carbon-aluminum frame
- Extensive harness customization including torso sizes, hipbelt sizes, and S-straps
- Burly 400D Robic nylon resists heavy abrasion and trail punctures
- Oversized hipbelt pockets comfortably house large phones and daily rations
- Heavier than minimalist sub-two-pound competitors at over 2 pounds 6 ounces
- Non-taped seams require an internal liner bag for full waterproof protection
- Body-contact backpanel provides less airflow than tensioned trampoline frames
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