Weighing in at a mere 8.6 oz, this is the second lightest jacket in our review. While this featherweight won't keep you warm sitting on a lift or huddling at a belay, our testers found it to be the perfect layer for continuous movement like running, scrambling, and hiking. The Atom SL (superlight) feels almost as light as a windbreaker, with no insulation in the hood and a thin mesh lining in the arms. Thin panels of Arc'teryx's proprietary insulation, Coreloft compact 40, strategically sewn into the chest and back, make this "windbreaker plus" a specialized piece that delivers the warmth of a fleece for less weight, more compressibility, and some weather resistance.
Arc'teryx Atom SL Hood Review
Compare prices at 2 resellers Pros: Super light, breathable, good mobility
Cons: Doesn't stuff into its own pocket, not very warm
Our Analysis and Test Results
Lightweight and breathable, the Arc'teryx Atom SL is a good choice for activities where you are constantly moving. In past years, this jacket has been the lightest of the bunch, but now it's been surpassed by the Patagonia Micro Puff, a much warmer, more weather resistant layer at nearly the same weight. Still, this contender is highly breathable and is designed for totally different applications than the Micro Puff, making it a good choice for crisp fall runs.
The intention of this piece is to provide maximum breathability while keeping a heavy breathing, hard-working human in motion protected from wind and light precip. It does this very well. The Coreloft 40 kept our testers toasty for a few minutes during a mid-hike snack break, but after ten minutes of sitting around cooling down at about 8,000 feet, they were reaching for something loftier to throw on top. The Patagonia Nano-Air Hoody is heavier and bulkier, but it provides more warmth with slightly less breathability.
Weight and Compressibility
At 8.6 oz, this jacket came everywhere with us and it was easy to forget about when stuffed down to the size of a grapefruit in the top of a pack. We really wish there was a stuff pocket with a clip in loop so we could clip this jacket to a harness when the sun comes out. The Atom SL is 4.9 oz lighter than the Patagonia Nano-Air Hoody, and it takes up about half of the space of the Nano-Air when stuffed into a pack. It takes up about the same amount of space as the Outdoor Research Cathode Hooded Jacket.
The Atom SL has a bit of stretch in its tyono shell fabric and even more in the stretchy panels sewn into the sides underneath the arms. This provides for full mobility, even when the bottom of the jacket is tucked under a harness. To keep the jacket light and super compressible, there is no fleece lining in the pockets and no insulation in the hood. Our testers did find that the hood cinch kept the hood in place well, and it did a great job of keeping the wind off their ears. The clean, snug cuffs kept the cold out and fit tight on some testers' forearms.
Arc'teryx's durable waterproof repellent treatment is called Nu, and it does a good job repelling mist and light rain for a short time. After five minutes under running water, the sleeves and hood were completely soaked and our arms got wet. We started to see a small amount of water soaking through on the back and chest, but nowhere near as much as we expected for such a lightweight piece designed to breathe, not to be waterproof. In fact, we stayed dryer in the Arc'teryx Atom SL than the more heavily insulated Outdoor Research Cathode. The slim cut of the Atom SL makes it ideal for pairing with a rain jacket.
Our favorite thing about this jacket is that it breathes well enough that we rarely have to take it off. No stops mid-approach to de-layer; just unzip the jacket for the uphill slog, and keep going. If you run hot like our lead tester, this is the layer for early morning runs when it's any warmer than freezing outside. The Tyono shell fabric may not be as breathable as the stretch nylon of the Outdoor Research Uberlayer or the Patagonia Nano-Air Hoody but still breathes better because it has significantly less insulation.
The Atom SL stays right in line with what we've come to expect from Arc'teryx: simple, sleek, and clean. We really liked the athletic cut of this jacket. Our lead tester had no qualms about wearing the Atom SL straight from the cliff to the bar. Our test model was a low-key brown color, but other brighter colors are available for as loud of a statement as you want to make.
Think running on a crisp, breezy fall afternoon, multi-pitch climbing on a shady wall, or summer peak bagging in the Sierra. Activities where you are in constant motion, generating lots of heat from the inside, but you still need protection from light alpine conditions are where this piece shines. In the ever-changing fall weather, our testers found that they could leave it on all day.
At $229, it may seem like a lot of money for not a lot of jacket, but the value goes up when considering that the Atom SL is playing the part of a fleece and wind breaker. The high price comes with the excellent workmanship and attention to detail that we have come to expect from Arc'teryx.
The Atom SL is the lightest jacket in its category. It breathes well and takes up less space in your pack than a fleece and a windbreaker. This is not the jacket for hunkering down at a chilly belay, but it is the perfect layer for aerobic fun when the cold winds are blowing.
— Matt Bento