Arc'teryx Proton FL Hoody - Women's Review

The Proton FL is a do-it-all hybrid with stretchy wind-proof face fabric and ultra-breathable insulation for some extra warmth. It is great as an outer layer on warmer climbing days and as an insulating layer for winter backcountry adventures. If you crave more warmth but don't want to sacrifice breathability or mobility, then this just might be the jacket for you.

Performance Comparison

Cozy yet still breathable, the Proton FL is our Top Pick for a hybrid softshell.

Photo: Mary Witlacil

Weather Protection

The Proton FL scored quite well in this category. This is because it is water-resistant, wind-resistant, and fairly warm. It handles wind and light rain like a boss, as long as the temps don't drop too low. And when it does get too cold this lightweight jacket is easy to layer under something more substantial.

In our water-resistance tests, the Proton FL scored well above average, but not perfect. This shows that while tit is not an ideal rain layer, it does have above-average water-resistance for a softshell. Wind resistance is where the Proton FL really shines. It features two panels with proprietary Fortius Air 20 fabric which provide protection from the wind, while still being breathable. The Proton FL proved its merits when put to the test on a windy multi-pitch in January, keeping our reviewer fairly warm despite wicked strong winds.

With the hood up, the Proton is an ideal wind layer on windy multi-pitch days in Eldorado Canyon in later winter.

Photo: Scott Sinor

Without insulation, the Proton FL would just be a super-thin active softshell. With insulation, it is an active softshell on steroids. It is warm enough to be a fantastic insulating layer while ice-climbing or as a shell on windy days rock climbing. It is also warm and breathable enough to be a perfect outer layer for summer peak-bagging or alpine rock climbing, where temps can wildly fluctuate in the presence of wind or shade. The Proton FL handles wind, precip, and cold like a beast. We love it.

Breathability

Even though the Proton FL is insulated, it is shockingly breathable. It is basically magic.

Brisk uphill hikes have nothing on this jacket. Where most layers would leave you feeling swampy, the inner mesh lining on the Proton FL effectively whisks moisture away from the skin, while the Fortius Air 20 fabric allows body heat to escape even when your heart rate is high. All this works together to keep you dry while working hard in colder temps. When paired with another shell for ice climbing, the Proton is fantastic as a breathable insulation layer. It can get overly balmy on warmer days but is breathable enough to avoid the post-swamp chills. The impressive breathability of this jacket establishes how it could suit everyone from mountaineers, backpackers, backcountry skiers, bicycle commuters, rock climbers of all persuasions, and even ice/mixed climbers.

The Proton is an ideal layer for an early spring backpacking trip in Utah. It's great for staying warm during breaks but is ultra-breathable if you need extra warmth while hiking,

Photo: Dana Prosser

Mobility

The Proton FL ranked incredibly high in terms of mobility. It feels light on the body, and the articulated elbows and gusseted underarms make any activity accessible and non-restrictive. The hood is stretchy and allows unimpeded motion even when under a helmet.

The Proton FL offered unhindered mobility on a number of climbing routes and styles. It proved a worthy companion on all manner of routes — from granite multi-pitching in January and sunny late-winter days in Eldorado Canyon, to approaching ice climbing routes and as a do-it-all late-winter jacket in Indian Creek. There were rarely (if any) instances of hemline-creep or climber's crack. The hood is slim and fitted enough that it can be worn under a helmet without issue, and the fleece-lined pockets are great for warming hands between routes. One note: some reviewers feel the Proton runs a bit small in the arms and hemline — if you are between sizes or have wider hips, order the next size up. All-in-all, the Proton offers unrestricted movement with little exception.

As a hybrid softshell, the Proton is so stretchy and mobile that it's even a rad layer to have while ice climbing. You can see it just poking out from underneath the Mammut Ultimate V.

Photo: Michael Voth

Weight

In a size small, the Proton FL weighs 9.5 ounces, which is among the lightest jackets in our review.

The Proton FL is featherweight on the scale and feels shockingly light on the body. If you want a layer that can cover a lot of bases without weighing you down, this is an excellent candidate.

Is there anything the Proton can't do? This versatile jacket is even toasty enough to be used as an outer layer for warm approaches and descents to ice climbs.

Versatility

The Proton FL is easily the most versatile jacket in our review. We gauge versatility by considering the features, durability, aesthetic design, and the array of ideal activities/weather conditions for each jacket. The Proton met or exceeded expectations for each category, without exception. It is feature-rich and user-friendly, ideal for rock and alpine climbing, backpacking, hiking, bicycle commuting in chilly weather, and when paired with another layer is great for winter backcountry adventures as well.

While the Proton FL is not made to be an ideal layer for ice climbing, it could be worn as an outer layer on warmer days, or as an insulating layer on colder days. Our reviewer tested this jacket all over the mountains and the desert, taking it up granite chimneys and sandstone fist cracks. When it is paired with another softshell, it proved ideal for granite mixed climbing and swinging tools on hero ice in Ouray. The partially insulated hood on this jacket means you can use any type of helmet without overheating. It has two large chest pockets that provide good storage even while wearing a harness, and the hand pockets are softly lined to provide extra comfort and warmth. Both the hood and hemline are quick and easy to adjust to create a tight barrier against the elements, and the insulation is both protective and permeable. The cuffs aren't adjustable but are stretchy enough to fit over thin gloves and low-profile enough to slide under gauntlet-style gloves.

The Napoleon-style harness pockets make it easy to warm your cold hands between pitches.

Photo: Scott Sinor

Value

As with most things from Arc'teryx, this softshell does not come cheap. However, it is innovative, well-made, comfortable, warm-yet-breathable, and lightweight. If you want a comprehensive mid-layer that can stand alone or be part of a thoughtful layering system, the Proton FL is worth the hefty price tag. If you just need something simple for occasional use, this is likely overkill, and we'd suggest seeking out a less technical and more affordable model.

The Proton has not 1 but 2 (!) chest pockets. Enough pockets for all the snacks!

Photo: Scott Sinor

Conclusion

Often, hybrids don't function particularly well because they try to do too much at once. The Proton FL is the best we've had the pleasure of testing, hence the Top Pick Award. It is warm without being stifling, lightweight, stretchy while still providing surprisingly good weather protection, and the versatile features make it appropriate for many different kinds of activities. It is more durable than previous iterations and well-tailored, giving it a great aesthetic on and off the rock. It is fantastic as an outer layer in warmer temps or a light insulation layer in colder temps. This jacket is a fantastic all-arounder for those who have a hard time sticking to one activity or one season in the backcountry.

The Proton is a great way to stay warm on sunny winter days while multi-pitch climbing in Eldo, or wherever you may roam.

Photo: Scott Sinor