July 01, 2020





Polartec® Alpha® was invented because some things in life happen too fast to layer up or down. The U.S. Special Operations Forces (SOF) can think of a few, and for years there were no options on the market that could meet their specific needs — a breathable, quick-drying, and packable insulation for demanding start-stop activities.

So SOF approached Polartec​®​ with a brief to develop a versatile insulation technology that could remain comfortable through extreme temperature variations while operating in mountainous terrain. In other words, they wanted to eliminate the need to shed layers when things got hot in a combat zone or add them at rest. That's how the seeds were planted for the world's first Active Insulation.


The U.S. government makes an ideal partner when developing a new technology (see: GPS, the Internet, airbags, etc. ) because it can fund far better and more thorough testing than, well, anyone. Polartec Alpha came to be through extensive lab and field testing in extreme environments, including cold weather combat training in Kodiak, Alaska.

SOF prepares for fighting in miserable conditions and test clothing systems by walking into a river in spring or winter conditions with their entire PCU (Protective Combat Uniform) on, stay submerged for 15 minutes, then get out and walk the system dry. This is just one of the ways Alpha was tested, yielding scientific data and feedback for an in-depth report.​
FT Alpha Special Forces

Of all the Polartec​®​ fabrics tested by the U.S. Special Operations Forces' Evaluation team, Alpha received the highest marks. In 2012, the SOF Protective Combat Uniform Level 3A Jacket became standard issue for every Special Forces Operator, and it’s still in deployment today. This groundbreaking Alpha jacket replaces two to three layers, which reduces costs, saves weight in the field, and improves operational effectiveness. In short, Alpha simplifies dressing for cold weather start-stop activities.

The U.S. Special Forces called on the Science of Fabric to invent an entirely new category of performance fabrics. Before Polartec Alpha, Active Insulation simply didn't exist — but what exactly is Active Insulation, and how does Alpha achieve it?


Typical down and classic synthetic insulation are less formed, prone to migration, and can poke through lighter face fabrics. To keep these fibers in place, they must be sandwiched between high-density woven layers that create a vapor barrier. While such solutions will keep the wearer warm at rest, even minimal activity quickly results in sweat that then gets trapped, creating uncomfortable saturation. If a rupture occurs, you've got a real mess on your hands — especially in a combat zone where your position may have just been compromised by an explosion of bright batting.

FT Alpha Blog Fabric Illustration

Alpha is not a batting. Lofted fibers connect to a sturdy knit-lattice structure, creating a stable layer that allows for more air-permeable face and back fabrics. As the world’s foremost fabric finisher, Polartec was able to figure out how to brush this (nearly lacelike) open knit without ripping it apart.

The lattice shape permits a small amount of airflow that enhances breathability, so Alpha can be worn in a wider range of activities without the need to add or shed layers. Alpha's structural integrity also means it won't spill out in the unlikely event of a rupture or migrate into clusters that can create hot and cold spots.

In addition to unprecedented levels of breathability and moisture vapor transport, Polartec Alpha still insulates effectively while wet and offers dramatically faster dry times. This versatility means Alpha can be paired with pretty much any combination of facing or backing fabrics — or no fabric at all.


Polartec® Alpha® Direct insulation takes Alpha's features one step further with enhanced resiliency and durability. Alpha Direct's insulating fibers are uniquely shaped and sized to eliminate the need for a facing fabric. This visible technology offers direct warmth, increased breathability and compressibility, and even faster dry times, while reducing garment weight due to the lack of lining fabric.


Alpha's innovative Active Insulation enables hybrid product design that can combine performance attributes of base layers, insulation, and outerwear in a single garment. This renders the classic "layering system" approach to dressing for cold weather activity obsolete. Naturally, designers for categories across the consumer market have found new and surprising uses for this game-changing fabric technology.

For your convenience, we compiled a list of the finest uses of Polartec​®​ Alpha​®​ and Polartec​®Alpha​®​ Direct from brands in the cycling, outdoor, lifestyle, running, and tactical worlds who aren't afraid to rethink the traditional layering system.

OUTDOOR<a name="outdoor" />

4 FT Alpha Outdoor Marmot 700x700

Marmot Women’s Alpha 60 Jacket

With the combination of an ultra lightweight stretch woven face fabric and the lightest Alpha Direct we produce (60g, hence the name), our Product team insists this is "the perfect interpretation of how Alpha Direct should be used." Available for men and women, consider this jacket a point of reference for any brand designing aerobic wear with Alpha Direct.

1 FT Alpha Outdoor Stio 700x700

Stio Women’s Alpiner Hooded Jacket

Stio's collection of lightweight, hooded insulators is available for men and women, as are the half-zip versions. We love the no-nonsense design that allows Active Insulation to take center stage and provide breathable comfort year round in a mountain town.

3 FT Alpha Outdoor Mammut 700x700

Mammut 3850 Bomber Jacket

This modern bomber is Mammut's tribute to urban lifestyle. Alpha helps a classic outdoor brand break out of its comfort zone with a unique and multifunctional design that won't make you choose between high performance and street-ready style.

5 FT Alpha Outdoor Norrona 700x700

Norrøna bitihorn Alpha Shirt Hoodie

New for SS20, Norrøna's body-mapped hoodie puts three different Polartec® fabric technologies precisely where they work best during high-intensity activity. The bitihorn's hybrid construction is a testament to the Norwegian brand's attention to detail and a prime example of the Science of Fabric's impact on the Outdoor / Athletic category.

2 FT Alpha Outdoor Oiselle 700x700

Oiselle Insulated Vigor Vest

Oiselle offers a lightweight women’s running vest made with Alpha Direct Insulation for superior breathability and fast-drying performance, while shielding from wind and rain. It's perfect for running in frigid temperatures.

CYCLING + MOUNTAIN BIKING<a name="cycling" />

2 FT Alpha Roadie Giro 700x700

Giro Women’s Chrono Pro Alpha Jacket

It's never a bad idea to start prepping for the cold and rainy months, and this luxurious Alpha jacket from Giro will have you counting down the days until fall. Polartec® Windbloc® provides a wind-proof exterior, while Alpha Direct puts comfy, quick-drying insulation next-to-skin for the ride of dreams, even in the worst conditions.

1 FT Alpha Roadie Santini 700x700

Santini Redux Genio Vest

Santini's Alpha vest for women demonstrates why they lead the pack in Italian cycling. Instead of adapting collections made for men, Santini develops products specifically for women. They've packed tons of great features into the light and compressible Genio Vest, making it a perfect addition to a minimal kit for long-distance rides.

3 FT Alpha Roadie Fox 700x700

Fox Flexair Pro Fire Alpha Jacket

One of the most recognizable mountain biking brands gets in on the ground floor of Active Insulation with this rough and ready Alpha Direct jacket. The Flexair Pro Fire's exceptional breathability and weather protection keep you focused on the flow. Fox adds enhanced durability in areas prone to wear to ensure you're dialed for years to come.

LIFESTYLE<a name="lifestyle" />

2 FT Alpha Lifestyle Strafe 700x700

Strafe Men’s Alpha Shirt Jacket

This may just be the best all-around men’s Alpha shirt jacket on the market. Versatile 60g Alpha Insulation keeps the shirt jacket incredibly light and the options open for where this piece can go. It's a solid year-round companion for the mountain.

1 FT Alpha Lifestyle Roark 700x700

Roark Layover Jacket

This do-it-all Alpha Direct travel jacket acts as a companion piece to Roark's popular Layover Pant. Soft comfort, breathability, and plenty of pockets make the highly packable Layover Jacket an effective travel buddy.

3 FT Alpha Lifestyle 66 North 700x700

66ºNorth Hrannar Alpha Women’s Zipneck

Longtime collaborator 66ºNorth has found the balance between function and fashion with over a dozen Polartec® fabrics. With the Hrannar Zipneck (also available for men), the Icelandic brand once again adds their signature stylish touch, this time to Alpha Direct. The outward-facing, "naked" Direct makes for a slick Outdoor / Urban crossover pullover.

4 FT Alpha Lifestyle And Wander 700x700

And Wander Polartec Alpha pants

Tokyo-based brand And Wander built their reputation on aesthetically refined interpretations of Outdoor staples such as hiking shells, ultralight backpacks, and fleeces using the latest materials. Their Polartec Alpha pants deliver on expectations with a handsome take on ventilated insulation for added warmth anywhere.

TACTICAL<a name="tactical" />

3 FT Alpha Tactical MTHD 700x700

MTHD Aphelion Hybrid Full-Zip Jacket L3

MTHD is a relatively new brand specializing in tactical apparel. Their Aphelion Hybrid jacket pairs a tear-resistant, woven-faced Alpha insulation front body with Polartec® Power Stretch® Pro™ sleeves and back body. Both Polartec fabrics are treated with a durable water repellent for added weather protection, making this jacket a versatile option for adaptable comfort in start-stop activities.

1 FT Alpha Tactical Triple Aught Design 700x700

Triple Aught Design Javelin Anorak

Triple Aught Design has been one of the biggest adopters of Alpha, and this versatile pullover is among their best options for spring. With the combination of a weather-protective shell and Alpha Active Insulation, it's everything you need in a lightweight, standalone insulator for high-intensity activity in unpredictable conditions.

2 FT Alpha Tactical Beyond 700x700

Beyond Clothing A3 - Alpha Sweater

Beyond Clothing was founded by former Army Ranger, Rick Elder, who was involved in designing the first SOF Protective Combat Uniform (PCU) with Alpha. It comes as no surprise that he's still Alpha loyal, and the A3 Alpha Sweater closely resembles the standard issue PCU Level 3A — with the addition of a removable hood.


Alpha's development with the U.S. Special Forces is one of our favorite technology origin stories because it reflects our history of staying on the cutting edge of fabric technology and demonstrates what we mean when we talk about the Science of Fabric. Before SOF came to Polartec​®​ to develop this product, it didn’t exist. They searched high and low, scoured tradeshows, but the exact design solution they needed — breathable, adaptable warmth in start-stop activities — wasn’t available.

The Science of Fabric brought SOF's brief to life, and Alpha is yet to have an equivalent competitor on the market. Alpha's structural integrity is its unique advantage, inspired by our generational experience as knitters. Other fabric companies have knocked off NeoShell, they’ve riffed on fleece, but thanks to Alpha's knit-lattice structure, the Active Insulation game is still all ours.

We hope this list helped narrow down the search for a new springtime insulator or inspired the next great Alpha design. Polartec Alpha offers the most comfort throughout the widest range of temperatures and activity levels, so its uses are boundless. As always, Polartec​®​ is ready to push the Science of Fabric forward and make the impossible possible.

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