Arc’teryx Proton SL Hoody

I picked this up on sale at REI in a brighter blue color. I bought it replace a nearly 10 year old Outdoor Research jacket that is nearly the same design, but uses Alpha Direct instead of Octa. Thus, my intention with this was to use it while rucking in the winter months. Which I’ve done, but it’s so good, that I’ve moved it to my hiking kit instead.

This is one of the best mid-layers I’ve ever owned. It’s fantastic.

Materials & Specs

The idea here is a light wind shell, with lightweight insulation to maximize breathability, allowing for a mid layer you can keep on for longer periods of time while under high-exertion. The Proton line also is developed more closely for climbers, which means the cut favors needing a lot of articulation in the arms.

Lining: Polyester Octa Rachel knit Insulation, 98gsm – 100% Polyester

Body: Fortius Air 20 – Plain Weave, FC0 DWR, 58gsm – 88% Nylon, 12% Elastane

This Octa is very akin to the Polartec Alpha you might be more familiar with, and there’s no lining over it inside the jacket. Thus the insulation is right against your base layer. The body then has a very thin shell, which exists only to protect the lining and lightly shield you from wind. There is no rain protection here.

Wear & Use

The description:

The lightest, most breathable option in our Insulation Collection, the Proton SL Hoody takes the guesswork out of warming up on cold climbs and other high-output activities in cool conditions. The knit insulation holds its loft and shape—no matter how often you stuff it into the bottom of your pack. More importantly, it allows your body to breathe, so you’re not left a sweaty mess after you have to step on the gas to get through the crux.

My take: this description is spot on, I have no notes, and it is accurate as hell. I’ve tested this on cool & cold rucking in the early morning, as well as on peak climbs up hard trails in variable weather. It’s never not impressed me, and while I might have picked this up to be beat up for rucking, I quickly rotated it into my hiking collection as I can’t see a better jacket existing for most of the day hikes I do where there’s a chill in the air.

As mentioned, I’ve been wearing a jacket like this for years, but this one takes it up another notch. The jacket is light in weight, but still warm (somehow). I typically rate this as good to around 30°F over only a base layer, assuming moderate to high exertion. That means that for a walk at night in 30°F weather, you’ll be cold in this jacket over a t-shirt. But if you are rucking, or on a hard hike, you will hit the sweet spot.

On my first outing with this jacket there was very light misty rain, and I expected the jacket to have enough DWR to shed that off. I was wrong, and by the end of that workout, the exterior of the jacket was pretty wet, though I never actually felt cold wearing it. Which means that you need a shell layer to battle any moisture, as this jacket instantly wets out.

What is most impressive with the jacket is how well it dumps heat when you are exerting yourself hard. Sweat escapes better than any other insulated layer I have, and never leaves you feeling like you’re creating your own personal sauna. This greatly helps extend the duration you can wear this jacket, often meaning I would be able to keep this jacket on longer than other insulating layers on a variable output hike where the weather is cool to cold.

I tossed this on at a lower 8,400′ summit, where the winds were ripping at about 20-30mph and the ambient temperature was around 38°F. I was plenty warm, and the hood slipped over my cap easily enough that it helped keep that from being blown off in the wind. Had we stayed at the summit a little longer, I would have wanted more wind protection, but as it was I never got cold. The wind protection is moderate at best on this, if you own an Atom jacket, that has better wind protection. If you have a Gamma, layering it over the Proton SL will create a really robust warm and wind protected system.

The insulation and face material dries quickly, whether from sweat or rain, such that you don’t experience the discomfort of a super cold back from where your backpack was sitting for too long. It also helps manage any odor build up, as it dissipates quickly. It’s a bit magical with how quickly it dries.

I have only two complaints on this jacket:

The face material did start to pill in a high-wear area from my rucking. It’s not fully unexpected, but I had hoped this would not happen.

Because of the design, it can be hard to get a long sleeve t-shirt to slip all the way down the sleeves without holding the cuff of your base layer since the knit of the insulation can cause a lot of friction. Some slide through easier, some bind quickly. It’s a trim cut through the arms.

The cut is trim and long, with good articulation in the arms. You won’t feel the sleeve binding even when wearing a backpack over the jacket. Not only does the jacket feel freeing with how well it lets heat escape but with how well it moves also. It’s very comfortable to wear overall, and the collar and hood work well here, helping to keep heat around your neck if needed, such that you don’t need a neck warmer most of the time.

Overall

This is, perhaps, the best insulation mid-layer I own. It’s one of those items where I would instantly re-buy this for full price should something happen to this one. I certianly hope nothing happens though, I would hate to lose this great of a layer for any amount of time.

Very highly recommended.

Buy here, $280