The Hyperlite Mountain Gear Unbound 55 Backpack is an ultralight backpack weighing 29.8 oz (819 g) made with Woven Dyneema fabric and Dyneema mesh. This new version is a substantial upgrade from the previous model, with more durable fabrics, a better frame system, and female-friendly (S-shaped) shoulder straps. Together, they make the pack much more comfortable and functional, enough so that existing Unbound owners should consider upgrading to the new model.

• Color: Grey
• Spec Weight: 29.8 oz (819 g)
• Actual Weight: 29.8 oz (819 g) in a size large
• Gender: Unisex
• Volume: 55L internal storage, 9L external storage
• Sizing: Multiple torso and hipbelt lengths
• Frame: Contoured aluminum stay, foam back panel
• Load lifters: None
• Pockets: 6 (2 side, 1 front, 1 bottom, 2 hip belt)
• Hydration Compatible: No
• Material: Dyneema Woven Composite, 100D Dyneema Gridstop, Dyneema Stretch Mesh
• Seam-taped: Yes
• Pros: Tougher fabrics and mesh, effectively waterproof, good pockets, multiple torso lengths, excellent attachment points

Backpack Pockets and Storage

The Unbound 55 is a rolltop backpack that can be buckled together on top or along the sides using webbing straps, which are girth-hitched to the daisy chains along the sides so you can remove them if you don't need them. I prefer securing a roll top with them because I find that they provide better compression than just rolling the extension collar (the top of the pack) and buckling it on top. The top of the extension collar has a stiffener, making it easy to roll shut and helping it stay shut.

You can secure the rolltop to the sides with optional webbing straps attached to the side daisy chains.

The Unbound comes with huge side pockets that are great for storing multiple bottles, securing a tent along the side, and holding the bottom of a snowshoe if you hike in winter. The top of the side pockets has an elastic cinch cord for securing the contents. The Unbound does not have an internal hydration pocket or hydration ports, so you'll need to carry water in these pockets or in accessory sleeves attached to the shoulder straps.

The hipbelt pockets are similarly large and can easily fit a Smartphone and snack bars or gloves. HMG expanded its hipbelt pocket size a few years ago, so this isn't a net new change.

The side pockets can hold more than water bottles – in this case a tent body is held and secured to the side of the pack.

The pack also comes with two open stretch mesh pockets, one on the front and one on the bottom of the pack, which is a feature that's become popular with thru-hikers. The front mesh pocket is pretty unique: it has a top opening and a lower one about halfway down, held shut with elastic. It lets you access items at the base of the front pocket without unloading everything. For example, I keep my tent stakes at the base of the front stretch pocket, and this lets me access them easily.

The bottom of the pack has a pocket you can use for snacks, hats, or gloves.

Both the front mesh pocket and the pocket at the base of the pack are made with highly durable Dyneema stretch mesh, since these zones experience considerable contact with the ground. The bottom pocket is a convenient place to store small snacks and trash, or hats and gloves, as long as you don't mind crushing the contents or getting them wet when you take the pack off and set it on wet ground. It has two openings: one on the right when facing forward and a small hole on the left, called a trash port, so you can stuff used wrappers into it.

The Dyneema mesh pockets on the UnBound are highly durable and unlikely to rip with regular use.

Backpack Frame and Suspension

The Unbound 55 has dual contoured aluminum frame stays augmented with foam padding behind the shoulder straps for increased comfort. They terminate behind the lumbar pad at the base of the pack, providing much better load transfer to the hips. This is a major upgrade from the previous version, which had only one internal stay and is more comparable, in terms of load transfer and stability, to the HMG Southwest and Windrider backpacks, making the Unbound comparable to those mainstays of the Hyperlite product line in functionality and comfort.

You tighten the hipbelt by pushing the straps forward, and it's much easier and more functional.

Take, for example, the UnBound hipbelt, which you tension by pushing the straps forward using what's called a Scherer cinch, named after Michael Scherer, who first designed it at Kelty. I get a much better hipwrap with the Unbound than the Southwest, which has been my backpack of choice for many years.

The Unbound's shoulder straps, like HMG's other packs, are now S-shaped, making them more female-friendly. They are covered in front with daisy chains so you can easily attach accessory best-of-breed pockets, like the HMG shoulder strap pocket shown, bottle sleeves, or electronics to your shoulder straps. Hyperlite sells a full range of pack accessories.

External Attachment Points and Compression

The Unbound 55 has low-profile daisy chains sewn along the main compartment's side seams that you can use to secure bulky gear like fishing rods or packraft paddles to the sides of the pack. The pack comes with elastic cords for this purpose, but you can use your own instead. This is more difficult on Hyperlite's other packs, which offer less flexibility in strap placement. If you've ever lost a fishing rod because it's popped out of a backpack's side pocket, you'll really appreciate the intricate webs you can design to keep from losing precious cargo.

The daisy chains give you the flexibility to secure many kind of objects to the side of the pack. The criss-crossed cord here ensures these Tenkara rods won’t be lost.

Comparable Ultralight Backpacks w/Frames

Recommendation

The Hyperlite Mountain Gear Unbound 55 is an excellent ultralight backpack for multi-day backpacking trips, excelling across a wide range of trail conditions and gear needs. It differs from Hyperlite's other backpacks in pocket size and placement, offers a more adjustable hip belt, and provides more flexible external attachments.  This new version also represents a major upgrade in two key components: a switch from a single aluminum stay to dual stays and the use of woven Dyneema as the pack fabric, making it significantly tougher and abrasion-resistant. The new grey-silver color is also pretty cool.

The upgraded Unbound 55 is so impressive that owners of the previous version should consider upgrading if their existing pack is nearing the end of its life. It also wouldn't surprise me if the Unbound becomes the most popular pack in Hyperlite's backpacking line, even outshining the Southwest and Windrider backpacks, because the hipbelt is easier to tighten and fit and the pack is more functional with no added weight gain.

Disclosure: Hyperlite Mountain Gear donated a backpack for review.

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