Review: Arc’teryx Proton FL


Arcteryx recently released the Proton FL, a soft-shell hoody that moves with you, sweats with you and packs away when you don’t need it. It uses a Fortius Air 20 fabric which gives it light air permeability and has good breathability from the Octa Loft, the 100% polyester breathable insulation. This good looking hoody will make a great addition to a mountain layering system.

Arcteryx Phantom FL on a ski day

Features & Specs:

Outer: Fortius Air 20

Insulation: 100% Polyester – Octa Loft

Weight: 320 g / 11.3 oz

Fit: Athletic Performance Cut

Best Use: Rock Climbing / Alpine Climbing

Arc'teryx Proton FL
Arc’teryx Proton FL On Tantalus Traverse

Tantalus Traverse: Trip Report Here!


Uninsulated Hood

Starting top down, the Proton FL uses an uninsulated hood that will fit under a helmet. The panel under the arms are also uninsulated for better breathability.

Waist synch

No interior pocket keeps this jacket sleek and low profile.

The exterior pockets are simply great. They have a soft fabric that will warm up your hands quickly while wicking away the sweat.  It is perfect for holding your extra gloves or granola bar. This hoody also has two simple pockets on the chest.

As most jackets in the Arcteryx climbing line, the Proton FL has foam inserts for keeping the bottom of your hoody under a harness.

Cut And Fit:

The Proton FL has a great athletic fit. It is slim through the core.

Any layer used for climbing needs to have unrestrictive movement in the shoulders. I found the Proton FL has good motion that didn’t  bug me while climbing. The arms are a healthy length too.

Around the waist was my only complaint. The tapered cut goes from longer in the back to shorter in the front. I felt that it may have been over done and the front could have been a little longer. This was only noticeable when wearing a harness and climbing.

Arcteryx Proton FL
Arcteryx Proton FL


So we know the jacket fits well, moves well, and honestly looks pretty great. The main question is how does it perform?

Answer, not too shabby. Overall I was very impressed with the warmth and breathability. I have used it Spring / Winter / Fall for ski touring, climbing, and alpine running, plus daily use around town. This hoody is a great active layer for those cold days when it’s hard to regulate your body temperature.

I normally prefer jacket hoods to have an over the helmet fit, but I never noticed it to be a problem on the Proton FL. Times when I wanted to have my hood up, I just threw on a proper jacket. The uninsulated hood also feel rather comfy under a helmet and has good protection from the wind. It does breath well in the front panels but if you are wearing a pack you could potentially get some back sweat build up on your back. This happens with any layering system though. A big thing that is worth noting is how fast this soft shell drys, even when it got all wet, I would still feel warm and it never stayed wet for very long!

The zipper on this jacket was the only other area that kinda bugged me. It would work itself undone sometime if I was wearing a heavy pack, it was advertised as a “No Slip Zip” but didn’t preform like one so I feel the need to point that out.

Pros:  Stretchy, well fit, fast drying

Cons: Short in front, zipper slips with heavy pack

Overall:  Great layer to have for any activity in the mountains



Arcteryx gave us this hoody for testing but in no way did it influence our review.