To improve your shopping experience today and in the future, this site uses cookies.
I Accept Cookies
The Proton FL is a synthetically insulated jacket designed with breathability in mind. The air-permeable outer fabric makes it perfect for use as a midlayer in worse conditions or an outer layer when moving quickly. 
The Proton FL is a synthetically insulated jacket designed with breathability in mind. The air-permeable outer fabric makes it perfect for use as a midlayer in worse conditions or an outer layer when moving quickly. 

Arcteryx Mens Proton FL Hoody Black

Click & Collect for Free
 in Customer Rewards when you buy this item today

With Pre-Order, you can purchase the latest items added to our store in advance of them arriving with us.

Your Pre-Order is prioritised (at no additional charge); meaning that as soon as the product arrives with us, we can wrap it straight back up; ready for collection via Click & Collect or despatch to you — it often never even hits the stock room shelves!


With Pre-Launch, the date when we expect to receive the product ourselves is still a little too hazy to be confident in accepting Pre-Orders.

So, instead, you can submit your email address against the item you are interested in and we will email you as soon as stock arrives on the system.

Estimated Delivery & Collection Dates

Estimated Delivery & Collection Dates are given on Pre-Order and Pre-Launch products. They are for indication purposes only and can change at any time without notice.

The dates we provide are based on indications given by our suppliers. Whenever we get updated information from our suppliers we will endeavour to update the Estimated Delivery & Collection Dates provided on product pages.

We estimate this will be ready for despatch to you or collection via Click & Collect on the Undetermined

Arcteryx Mens Proton FL Hoody Black Information

Season : 2020W A

Brand : Arcteryx

Code : 26443-BLA-

What is the Proton FL?

If you're familar with Arc'teryx's hugely popular Atom, you'll recognise where the Proton gets its good looks from. Don't get them confused though, these are two very different beasts! The Proton is designed with exceptional breathability in mind, whether that's as a midlayer in worse conditions or as an outer layer when moving quickly.

What is it made of?

Insulation: Providing the warmth inside the Proton is an air-permeable (wind passes through) Octa Loft insulation. This synthetic insulation will still provide warmth when wet, will compress down to a fraction of its original size and is nice and easy to take care of. 

Outer fabric: The primary feature of the Proton is its outer fabric. Unlike the majority of insulated jackets which will feature a wind-resistant outer fabric, the Proton's is air-permeable, meaning air can pass through. This means that the insulation traps your warmth, but air can pass through to cool you down when you're working hard. Think of it like a tent; you open the vents to allow air to pass through to provide a comfortable micro-climate, much like the inside of your jacket. Despite its exceptional breathability, it will repel water and is tough enough to put up with the abuse that climbing and mountaineering have to offer. 

What are the features?

Starting at the top, you get a helmet compatible uninsulated hood, two chest pockets, two hand pockets and lastly holes in the hem to allow you to insert a tubular piece of foam to prevent the jacket slipping up when wearing a climbing harness.

How does it fit?

Much like an Atom! If you haven't tried an Atom, the Proton fits into Arc'teryx's 'trim' fit block and is a regular/slight short length, features plenty of room in the shoulders and feels brilliant when on. For reference, the centre back length is 77cm.

Where does it fit in the layering system?

The Proton, due to its fantastic breathability, can either be used as a midlayer with a shell over the top or an outer layer when moving quickly. 

  • Exceptionally breathable
  • Water resistant
  • Air-permeable
  • Two hand pockets
  • Two chest pockets
  • Uninsulated hood
  • Hemlock holes

How Should Your Insulated Jacket Fit?

Insulated jackets are pedantic little things. Too tight and you'll compress the insulation and limit the warmth capabilities of your brand new jacket, too loose and you'll spend hours warming up the dead space inside the jacket. Getting the correct fit isn't just about aesthetics, it will determine how warm you are. 

The Incorrect Fit

Too loose: A jacket which is too loose will keep you relatively warm, however it will take far longer to do so and will waste large amounts of your precious energy. An insulated jacket works by trapping the natural heat that your body gives off in the fibres of the insulation; this creates a micro-climate inside your jacket, keeping you warm and toasty. If your jacket is too loose, heat will be able to escape through the hem, the sleeves and the neck of the jacket; it's a little like sticking the heating on in your car with the windows cracked open - it will heat up, just incredibly slowly.   

Too tight: A jacket which is too tight is arguably worse than one that is too loose. If your jacket is far too tight, the baffles can compress to a point where the insulation can't loft effectively, limiting the amount of warmth it can trap. Essentially, it won't work! 

The Correct Fit
It's a tricky one to explain, but it's somewhere in the middle. You've first got to consider how many layers you'll tend to wear underneath; will you have just a t-shirt then the jacket, or possibly a baselayer, midlayer and then the jacket? When you've figured out your layers and you've popped your insulated jacket over the top, you shouldn't have any dead space inside. The cuffs and hem should be comfortably sealed around your waist and wrists with room to move. You should be able to lift an arm up above your head without the hem of the jacket lifting more than an inch or so, and the sleeves should be long enough that when carrying out the same motion, they aren't mid-way up your forearm. Your shoulders and chest area should have enough room so that your hands can touch behind your back without feeling restricted. 

Additional Information
Lastly, consider which activites you'll primarily be carrying out while wearing the jacket. Are you primarily using it as a winter climbing piece, or an everyday/dog walking jacket? You'll find that technical climbing jackets tend to feature a shorter cut, while urban and casual jackets feature a longer cut to offer additional warmth with less mobility.

To see examples of what a badly fitting and correctly fitting jacket looks like, click here.

Technical Information

Weight: 340g


- Fortius Air 20 (84% nylon, 16% elastane)

- Octa Loft (100% polyester)

Sizing Information

Arc'teryx Men's Jackets & Shirts Sizing Information

Measurements refer to body size, not garment dimensions.

  Chest Waist Hip Sleeve
X-Small 36" 29" 36" 32"
Small 38" 31" 38" 33"
Medium 40" 33" 40" 34"
Large 43" 36" 43" 35"
X-Large 46" 39" 46" 36"
XX-Large 50" 43" 50" 37"
  Chest Waist Hip Sleeve
X-Small 92cm 74cm 92cm 81cm
Small 97cm 79cm 97cm 84cm
Medium 102cm 84cm 102cm 86cm
Large 110cm 94cm 110cm 89cm
X-Large 118cm 99cm 118cm 91cm
XX-Large 128cm 110cm 128cm 94cm

Next to Skin Fit: Cut snug to the body through the entire garment to enhance moisture management and thermal efficiency.

Slim Fit: Cut slim to the body through chest, waist, hip and thigh for a low profile fit.

Regular Fit: Cut comfortably from the body through bust/chest, waist, hip and thigh for a classic fit.

Relaxed Fit: Cut loosely through the waist, hip, and thigh for a casual fit.


Measure around your chest/bust, holding the measuring tape under your armpit.


Measure around your waist at the narrowest part.


From a standing position, measure from your crotch to your ankle.


With your arms in a slightly bent position, measure from the centre of the back of your neck, along the length of your arm, to the wrist.


Measure around your hips at the widest part.

Professional Opinion
Product Reviews
Write a review
0 As rated by 0 Customers

Write a review for Arcteryx Mens Proton FL Hoody Black

Your name
Your email address
How would you rate it?
Would You Recomend this product?
Let others know your opinion
Submit Review Close
Question(s) answered about this product
Ask a question
Questions asked regarding Arcteryx Mens Proton FL Hoody Black

Ask a question

Your name
Your email address
Your Phone Number
Your question
Submit Question  Close
Home Clothing Arcteryx Jackets

Be the first to know

Signup to receive the latest news and offers, straight to you inbox.