If you thought that the only place to buy ultralight cuben fiber stuff sacks is from cottage gear manufacturers, you’d be wrong. Granite Gear makes excellent waterproof roll-top cuben fiber dry sacks. Called eVent Uberlight CTF3 Dry Sacks, these cuben fiber stuff sacks have the added advantage of a breathable eVent air purging panel on the bottom which allows air to escape when the sack is compressed.
Granite Gear’s eVent CTF3 Uberlight Dry Sacks are available in four sizes:
- 7 Liter (weighing 15 grams/0.53 ounces)
- 10 Liter – (weighing 17 grams/0.6 ounces)
- 13 Liter – (weighing 19 grams /0.67 ounces)
- 18 Liter – (weighing 21 grams/ 0.74 ounces)
The beauty of using cuben fiber stuff sacks and dry sacks is that they weigh almost nothing and can help you keep your gear dry and organized inside your pack. As a point of comparison, a Sea-to-Summit 8 Liter silnylon waterproof dry sack weighs 1.1 ounces, or about twice as much as the same volume in cuben fiber.
Granite Gear’s eVent Uberlight Cuben Fiber Dry Sacks are taped rather than sewn, which is what you want for waterproof cuben fiber dry sacks (the stiff roll top rand is sewn and taped – but it has to be for strength.)
All of the sample bags I received from Granite Gear were green, although other colors are available (orange, blue, and yellow). This is handy if you like to color-code your pack’s contents. The green stuff sacks are also nearly transparent, allowing you to identify their contents, which I consider a very nice feature.
Granite Gear includes several transparent repair patches with each dry sack since cuben fiber is susceptible to puncture, although you have to go out of your way to do so. The fabric is very resistant to tearing however, unless you try to overstuff a stuff sack with contents that are way too big for the bag size. However, when that happens you’re much more likely to blow out the seam rather than rip the fabric, but this is true of any dry sack, regardless of the material it’s made with.
Air Purging Panel
The air purging panel on Granite Gear’s eVent Uberlight cuben fiber dry sacks lets you squeeze out any remaining air inside the sack after you roll the top closed. While you can see the air bubbling out of the bottom if you hold the dry sack in a pool of water and squeeze, there are times when the rate of purging is imperceptibly slow. This occurs when the contents inside limit the flow. For example, if the cover of your sleeping bag or quilt covers the inside surface of the air purge panel, the rate of airflow is slowed markedly. Air is still being purged, but you’ll have to sustain pressure on the bag much longer to see the shrinkage occur.
However, once extra air is purged, it will flow back into the dry sack unless you roll the dry sack top tighter or push the sack into a tight space in your pack where the contents will stay tightly compressed. I found this counter-intuitive and expected the eVent Uberlight air purge mechanism to work like the airplane travel compression sacks that you can get from Eagle Creek, which permanently exclude air when compressed.
When contacted, Granite Gear confirmed that air can flow back into the eVent Uberlight cuben stuff sacks even after it’s been purged. “It is normal for air to come back into a Uberlight sack. The material at the bottom, eVent, has pores sized so that air molecules can pass through it, but water molecules, which are much larger, cannot. In terms of the migration of air molecules, it is not a one-way deal—air will pass through the material to equalize inside and outside pressure as needed. All waterproof-breathable membranes are like this. In using the sack, you should use the roll down top to compress the contents and expect there to be a small amount of rebound afterward.”
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I guess I don’t understand the added practical value of having stuff sacks that refill with air after you’ve compressed them, especially given the premium price that Granite Gear charges for the Uberlight stuff sacks, compared to prices from other cuben fiber dry sack manufacturers like Zpacks, Hyperlite Mountain Gear, and Mountain Laurel Designs.
While I can get most of the extra air out of a dry sack by pressing down on it with my arms or a knee, I’d be willing to be more for dry sacks that purge the air permanently, like Eagle Creek’s travel compression sacks. But I’m not willing to pay a premium for dry sacks where the air flows back in. That doesn’t make any sense.
I’d give the Granite Gear eVent Uberlight cuben fiber dry sacks a pass unless you get them at a huge discount or can’t buy gear from other cuben fiber dry sack manufacturers because of the added expense of custom’s taxes or offshore shipping. The eVent Uberlights are still perfectly good cuben fiber dry sacks, but not at a premium price.
Disclosure: Granite Gear provided Philip Werner (SectionHiker.com) with the sample eVent Uberlight stuff sacks reviewed in this article.Editor's note: Help support this site by making your next gear purchase through one of the affiliate links above. Click a link, buy what you need, and the seller will contribute a portion of the purchase price to support SectionHiker's unsponsored and independent gear reviews, beginner FAQs, and free hiking guides.