Gossamer Gear Alchemy Mirage Review: Hiking with the Lightest 40L Pack Made

How Gossamer Gear Made the Lightest 40L Backpack Available

The Mirage is made of the thinnest version of Aluula Graflyte fabric, an exclusive UHMWPE fabric used in backpacks, called V52. Much of the hype around the Mirage and Gossamer Gear’s Alchemy Collection as a whole revolves around this material, which only a few brands are using in outdoor gear. For a little background, Aluula Graflyte is one of the newest and hottest fabrics on the market, and like all of the premium ultralight fabrics, it originated with windsports. It’s coveted for its waterproofing and high strength-to-weight ratio—the stuff is stronger than steel gram-for-gram. Take everything great about Dyneema, another well-known super-strong ultralight fabric that was once niche but has become well known, and make it better (and more expensive), and you get Aluula Graflyte.

Aluula uses a “molecular fusion” adhesive-free design that ditches the weight of glue. In UL world, every gram counts. More importantly, the construction minimizes delamination over time, which is a problem that plagues other popular UHMWPE fabrics. The lack of adhesives also keeps the fabric recyclable and easy to repair. It won’t unravel if you get a tear in your pack and it can be heatbonded, enabling more advanced designs from manufacturers.

That's how Gossamer Gear built the Mirage, by heatbonding the seams and using a little bit of interior seam taping instead of sewing them, which is how some other gear companies have deployed the material. In fact, no other brand has heatbonded Aluula yet, and no other brand has used V52, so it's no exaggeration to say this pack is one-of-a-kind. Not that many brands could make it even if they wanted to—in the backpacking world, currently only Arc’teryx, Nashville Packs, Durston Gear, and Mountain Hardwear (as of spring 2026) have been able to get ahold of Aluula.

When you combine the lack of glue in the fabric and lack of seams, you get a pack that is well positioned to be the lightest of the lights. Which is exactly what Gossamer Gear was going for with the Mirage—at 18.7oz, the company claims it’s the lightest 40-liter backpack on the market, outperforming even frameless packs.

In keeping with their quest for peak lightness, Gossamer Gear used 0.125 carbon fiber rods for the frame. The Mirage only comes in one length but the frame is adjustable for small to large torsos (specifically, 16 to 20 inches). The frame connects to the hipbelt for efficient load transfer. You can’t swap the EVA foam hipbelt out like other Gossamer Gear packs but it is adjustable to fit waists 28 to 44 inches.

Like most ultralight packs, the Mirage does not have any internal organization—it’s just one main chamber. For external organization, the pack has two water bottle pockets on either side and a stretch mesh front pocket. The design is very clean, without any extra pockets on the hipbelt or shoulder straps. You can buy a shoulder pocket and hipbelt pockets separately, but that will slightly increase the weight to 19.4 ounces with all accessories. It has thin compression straps at the top and uses a roll top design instead of Gossamer Gear’s traditional over-the-top closure. It is also compatible with hydration bladders and has a hose port at the top of the pack.

How I Tested the Gossamer Gear Mirage 40

In the past 10 years, I’ve thru-hiked 7,000 miles, almost exclusively with some variation of an ultralight pack. These packs ranged from my 2016 Hyperlite Mountain Gear Southwest to a Mountain Lauren Designs Burn at the smallest, and I’ve used packs by just about all of the major ultralight brands. I also spent a few years working in the backpack department at REI and other small gear shops many moons ago, so I have a solid knowledge base of backpacks and how they should fit and perform for a variety of uses and body types.

I tested the Mirage on a three-day winter backpacking trip in Dark Canyon in Utah. This is an early review, so it doesn’t extensively test the performance of Aluula Graflyte V52 over a longer period, like six months, or the course of a big thru-hike. That said, I specifically chose a route that I thought would involve some scraping against vegetation and rock walls to test the abrasion-resistance of the materials.

Dark Canyon is extremely cold in January so I packed a heavier winter kit for this trip. I skew towards the super ultralight side of the spectrum, and my pack totaled around 17 pounds with food and water, well below the bag's 25-30-pound threshold.

Testing Impressions

Comfort

The Mirage is an incredibly lightweight pack, and the fact that it has a frame is all the more impressive. It's leagues lighter than my old Hyperlight Mountain Gear Southwest (29.7 ounces) and ULA Circuit (38.5 ounces) packs. It’s even lighter than my ultraweave Pa’lante Desert Pack (20.9 ounces), which is notable considering that the Pa’lante is fundamentally a featureless stuff sack with straps. Both the mesh pocket and Aluula fabric on the Mirage feel thin—concerningly so—but that’s the point.

The one-size-fits-most nature of the Mirage means that it won't work for everyone, but it will work for more types of hikers than it would seem. Setting up the pack for size isn’t intuitive but it's simple once you watch Gossamer Gear’s instruction video. It’s not a perfectly accurate system so I guessed where the small-medium range would be and felt like I landed on a pretty good spot. Like with every backpacking pack though, it will help to know your torso length. Gossamer Gear does provide instructions on how to figure out your size, if you have a tape measure at home.

My torso is near the bottom of the range at 17 inches, so the frame sat pretty high on me, which is something I’ve never liked about framed packs. I have ardently avoided any sort of frame bag since REI told me to start the Appalachian Trail with an Osprey Aura a decade ago. Everything about them is a little baffling—why do they sit so high above your head? Isn’t it annoying to bump your head constantly? Truly, what is the obsession with airflow? Aluminum stays, maybe. But a real deal frame? No way.

Unfortunately for my super ultralight pretensions, I have to admit that this was the first time I finished a hike without shoulder pain. My shoulders are happy but my ego is a little bruised and that's a far deeper wound. I do think this is a unique benefit of the Mirage that doesn’t apply to all framed packs though—my shoulders were screaming in that Osprey Aura and even lighter packs with stays like Hyperlite's leave my shoulders raw. The Mirage appears to be a particularly great combination of a well-designed frame and ultralight kit, and I don’t think hikers who load the pack beyond its 30-pound capacity will be quite as comfortable. And much as I don’t want to entertain frames in ultralight backpacking, there is definitely a demand for them—just look at the popularity of the Zpacks Arc Haul packs.

I might just be too cautious with fragile materials but I wasn’t able to pull the frame taught enough to get any real airflow from the frame. Realistically, this is not your overbuilt REI pack that advertises to folks who can’t bear the thought of a little bit of sweat. I don’t think that kind of design has a place in ultralight backpacking—It’s hiking! You’re going to sweat!—so I didn’t feel a great loss in this, but hikers transitioning from maxed out lux packs to lighter gear may bemoan their new sweaty backs.

I did have one complaint about the frame, though I don’t think it will apply to the Mirage’s target audience. Hiking in southern Utah tends to be an engaging endeavor, involving down climbing, butt scooting, and ledge crawling. Whenever I would move in a way that wasn’t an upright bipedal stride, I could feel the frame’s adjustable buckle press into my spine. I didn’t notice it when I was strolling along normally, which is what I expect most hikers using this pack will be doing, but it seems like an odd placement for a large metal and plastic buckle. There is a flap that covers the buckle in larger sizes so this is an issue for shorter torsos only.

I don’t have a ton of comments on the shoulder straps and hipbelts because the EVA foam and shape are comfortable and did their job well. They’re neither beefy nor too thin. Gossamer Gear’s Skala pack (which I love) doesn’t have a great way of carrying a camera case so I was glad to see the daisy chains on the Mirage’s straps. The sternum strap positioning is easily adjustable, which is key for women hikers. The webbing on the hipbelt pulls inward, which is something other users were particularly clamoring for because it’s a more ergonomic shoulder movement to make the adjustment. I honestly don’t feel like it makes that much of a difference but I’m down with better design, even if it's incremental.

I did struggle with the add-on hipbelt pockets though and am certain that I would lose at least one of them on a thru-hike. They slide onto the hipbelt easily but they slide off even more easily with gravity when you take your pack off. I felt like I was doing something wrong but I think you really are supposed to just slide it on; to stay in place, it needs to have some sort of attachment more like the shoulder pocket. There’s no way of doing this though so I don’t really have an answer for this one.

Durability

I did my best to rub the pack against rock walls while ledge crawling and slipped once down the crumbly Sundance Trail, but there is no real substitute for thousands of miles on trail. Aluula is supposed to be UV-resistant but you can’t replicate the effects of time and sun exposure in an early review. The Aluula held up fine to the abrasions; the mesh did not. Some small holes developed on the bottom of the front pocket after I fell on shifty talus, but given how thin the mesh is, I expected this to be the failing point of the pack. I don’t find it that concerning because the way I used the pack is not really its intended use case, but months of dropping a pack on the ground will definitely lead to tears in traditional hiking scenarios. This pack needs to be babied.

I’ll note that my old Gossamer Gear Gorilla also developed holes in the mesh more quickly than any other pack I’ve used, so it’s just the nature of the mesh that the company uses. It’s fine in a pack that is designed to be the pinnacle of lightness but could stand to be replaced in their more durable packs.

The side pockets are much sturdier but this meant that I couldn’t fit two Smartwater bottles in each. Not using stretchy material or elastic tops is something I’ve noticed on a lot of new ultralight packs and it’s not a trend that I particularly like. I always carried four bottles on thru hikes, even the alpine ones, and the side pockets are key to that. Because the Mirage has a bladder port it’s definitely catering more to that hose-slurping hiker though, so it is what it is. I could at least fit a bottle and a Tenkara rod, and the side lace compression straps keep tall items like the rod in place nicely.

Waterproofing

Ultralight packing is an art that I’m not going to fully get into here, but you should always be keeping your gear in a trash compactor bag or some sort of liner. Even in more waterproof bags made from Dyneema and Aluula, you want that safety backup.

It didn't rain during my trip, so to test the waterproofing I threw the Mirage outside during a storm with a blanket stuffed inside. The rain was on and off and periodically heavy but mostly consistently drizzly. I left the Mirage outside from late morning to evening and it never soaked through. The mesh was soaked and water pooled on the outside of the pack but the contents stayed dry, so I think it’s safe to say that Aluula is sufficiently water-resistant.

Some folks with extended Aluula testing have commented on r/ultralight forums that it’s not waterproof, however, so I’m curious if its water-resistance reduces with time. Gossamer Gear’s heat-bonding definitely gives the Mirage a leg up over other Aluula packs. Either way, it’s not a drybag, so use a liner.

Who the Gossamer Gear Mirage Is For

I initially thought the Mirage was a clear competitor to the Durston Kakwa, one of the most popular thru-hiking packs on trail right now, but I think it’s actually more niche than that. I still think it can easily steal away some of those thru-hiking customers looking for even lighter Aluula gear but I don’t think it quite has the versatility of the Kakwa. When I need a pack that’s 40 liters or larger, it’s generally for burlier endeavors that require more gear, like cross country desert and alpine hikes. As much as I appreciate the weight savings, that’s not really the kind of trip where I’d bring the Mirage.

I think the Mirage is best suited for the ultralight comfort hiker—the kind of hiker who can afford all of the lightest things but still values their luxury items, like a two person tent, mummy bag, Helinox ultralight chair, sleep clothes, and so on. It felt a little too big for even my winter ultralight setup, so I think more dedicated ultralight hikers would prefer the smaller Murmur. This lines up well with Gossamer Gear’s core customer though—they’re known for being one of the most approachable ultralight brands, and while it's a very premium bag, the frame and capacity still make it suitable for hikers on the edge of the ultralight spectrum.

You don’t need to be the most hardcore ultralighter to appreciate the lightest 40-liter pack on the market, you just need to be a conscientious hiker with a predisposition for babying your gear.