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Hyperlite Mountain Gear Prism Pack

I’ve found that HMG has some of the most loyal and devoted customers of any brand around, and after over 6 months of heavily using the Prism I understand why.

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MSRP: $395

BEST FOR: Ice climbing, fast-and-light alpine climbing

High up on a face in Alaska this past May, my fingers were getting cold. My harness was getting a bit twisted. The gate on one of the carabiners at the end of my umbilicals, connecting me to my ice tools, had broken. It seemed like every piece of gear had something malfunctioning. Except for my pack: sure, I had 30 pounds of gear in it, but it was still comfy and snug. It felt barely there. 

I was using the Prism, Hyperlite Mountain Gear’s newest addition to its curated line of mountain packs. And it is their most technical yet, designed specifically for ice climbing and light and fast alpinism.

As with everything Hyperlite Mountain Gear makes, the Prism Alpine Climbing Pack is one of the lightest packs out there. Empty, the Prism weighs 1 pound 8.2 ounces (827 grams). Per HMG’s signature style, the 40-liter Prism is made almost entirely from dove-white Dyneema Composite Hybrids (DCH). More specifically, the main body of the pack is built of DCH150, while even stronger 375 Denier DCHW is used in the back, bottom and sides to limit abrasion as much as possible. The “frame” consists of a single, removable aluminum stay, shaped to run along your spine. Additional back support comes from a thin plastic panel and foam.

The Hyperlite Mountain Gear Prism Pack out in the wilds of Alaska.
The Hyperlite Mountain Gear Prism Pack out in the wilds of Alaska.

Starting at the top: this is where HMG has changed up their formula the most for the Prism. All of the other packs they manufacture have roll-top closure systems, similar to dry bags. While roll-tops help cut weight and are particularly good for keeping water out, they can leave ice climbers and alpinists wanting—they make quickly getting something out of your pack more of an ordeal. The Prism is the first HMG pack to get a traditional brain. 

The Prism’s brain attaches to the body of the pack via a horizontal strip of velcro and two adjustable G-hooks on either side. Another two G-hooks fasten the brain in the front, via daisy chains sewn on to the front panel. The brain is simple, but it’s all you need: one 3.5-liter compartment with a single zipper entry. Headlamp, extra gloves, energy bar, light shell, any other things you’ll need quick access to—that’s what this brain is built for. The velcro strip more often than not seemed a nuisance to me (if the pack is ever full, it just becomes something extra to get things stuck on), but in general the brain is a great feature that we’re glad HMG went with. 

Beneath the brain, the pack has two drawstring closures and a gray collar inside to give you more volume should you opt for a heavy-and-slow outing with more gear. The drawstrings are easily manipulable even with thick gloves. A number of times, if I was just out cragging in good weather, I removed the brain, streamlining the pack even more. If it’s looking like it’ll be a wetter adventure, best to leave the brain on, though. While the roll-top HMG bags are more watertight, unless you straight up dunk the Prism, it’s pretty close to waterproof itself if the brain is on. The gray collar is made of nylon so is slightly less burly and durable than the rest of the pack—just something to keep in mind, as your sharps are more likely to tear this part.

The Prism does the Tetons.

The carry systems for ice tools, crampons and skis are all simple and elegant. Rather than have a piece that fits through the head of the tool to lock it in place, as many packs do, the Prism has what HMG calls the “diamond” pocket. The geometry of this pocket—combined with more conventional bungees higher up for the tool handles—keeps your tools secure and snug without additional pieces or clasps of any sort. I found that the more aggressive the tools, the better the diamond pocket works.

For your crampons, there is a rectangular pocket in the middle of the front panel, with a strap to snug it down and a couple small holes at the bottom. This means you don’t have to put any sharps inside your pack, and if your crampons are caked in snow and ice, the pocket drains as your points melt out in warmer weather. 

For your skis, the Prism relies on an A-Frame carry system: strap a ski to each side with the two buckles and start hoofing it. Alternatively, these straps, in combination with a pocket on each side (in the spot where daypacks frequently have water bottle pockets) can be used for storing wands or pickets. My experience in Alaska led me to wish the pockets were a bit deeper and wider: When the pack is stuffed full, the pockets do not have any give or stretch (since they, too, are made of dyneema) and shoehorning a picket in there can be a struggle, or downright impossible.

What the Prism looks like when it's all loaded up.
What the Prism looks like when it’s all loaded up.

Finally, there’s the removable waist belt. The closed-cell foam was just enough cushioning against the hips that I never had any uncomfortable rubbing. On each side there is a large gear loop—each encased in plastic tubing—and an ice-clipper slot, great features when you’re in full alpine mode and climbing with the Prism on.  

One final thought: I’ve found that HMG has some of the most loyal and devoted customers of any brand around, and after over 6 months of heavily using the Prism I understand why. The company iterates upon every aspect and feature of their products, up until the final second, to ensure that everything has a purpose and functions how it should. Basic R&D? Sure. But it’s that much more important when we’re talking about shaving individual grams off of a product. 

I saw HMG’s rigorous process up close: I tried two prototypes of the Prism, in addition to the final iteration of the pack that HMG released in September. The final version was so subtly different from the penultimate prototype, that most people would never notice. But Hyperlite Mountain Gear realized that the change would help the Prism function better, so tinkered ever so slightly with the design.

At $395, the Prism costs a pretty penny. But the best gear always does.

Michael Levy


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