Me: 5'7, 135lb, size small in about anything, trail/ultra runner. I received this Atom LT Hooded Jacket as a tester product from Backcountry, though, these opinions are my own and not sugar coated. I've used this jacket on about 20 evenings in the Sawatch range of Colorado in a fair mix of camping, MTB, hiking, and trail running. Weather during use has ranged about 35-60 (it is August!) degrees so far, with dry conditions. In the past I've used down jackets from The North Face and Merrill, both size small. The Atom LT Insulated Jacket fits comparably to those brands and is otherwise a true small fit. It is not a dead-of-winter high alpine heavy jacket, but I can see an optimal range being about 35F to 10F, and even lower if using a hard shell. For a midweight jacket, it delivers what I demand of it. The Arcteryx Atom LT Hoodie was noticeably different as soon as I picked it up. It is not the typical down feather puffy, but a continual layer of a lightweight and lofty Cofeloft that is also arguably lighter than a comparable down jacket. From my use so far, thermal quality is equal to that of my typical 800 down jackets. The outer layer is very thin; comparable to the thickness of a tent. Then comes the insulation, maybe 3-5mm thick. You could almost think of it like the feeling of flannel completely wrapped inside a jacket shell. I've got the Squid Ink color. It is proper purple! (But I'm surprised with how good it looks as the first piece of purple attire I've ever owned.) It is August, and the middle of a drought, so admittedly my only exposure to water in this jacket was in the shower. No kidding! The jacket is not waterproof (and it doesn't claim to be), but light rain will fall off the jacket without permeating it. Heavy or prolonged rain does soak in, as expected, BUT, what is sweet about the Coreloft is that it is balanced and does not retain much water as down. Instead of having pockets of trapped water in a down jacket, the jacket still wears very evenly, and doesn't accumulate as much weight. I would opt for this before a down jacket in wet weather. The insulation material is impressive. The wrist cuffs are a thin poly type material that are stretchy enough to pull around a glove and comfortably get hand through. There is a drawstring at the waist to dial in a good fit. Inside the jacket on the left chest is a auxiliary zipper pocket to stash a phone, ski pass, wallet, etc. I really like that the jacket/zipper easily zips up past my nose. There is generous face coverage from the zipper and hood. The hood has a drawstring on the interior that allows it to draw skin tight and has a supportive "bill" on it to keep it from blowing in the wind. The hood is very well designed and has no problem in wind keeping my face/ears warm and staying on the top of my head! I have been able to roll this up into roughly the size of a can of Pringles - just a bit more in diameter - and keep it in a 18L running pack, complete with my other gear for a long day out. It is plenty packable for what it is. Overall, I am very impressed with this jacket. I would give a 5 star here, with my favorite features being the lightweight material and ability to shed away water. Though I received this as a test product, I certainly see it going into my everyday-use gear quiver.
Brandon Yonke, backcountry.com
August 26, 2020