Comparison Review: The Best Synthetic Insulated Jackets This Winter

Even though news of cherry blossoms is coming to the villages at this time of year, the bitter cold will continue for a while up in the mountains

Winter clothing to protect oneself from the cold has evolved and diversified remarkably in recent years, even within the category of mountaineering wear, and personally, it's one of the categories I look forward to seeing new releases every year. While there's no doubt that down is the best choice when it comes to lightness and warmth alone, it's also true that it can get quite stuffy and is resistant to getting wet, making it less practical for mountaineering. From a practical standpoint, synthetic insulation jackets filled with synthetic fiber padding would likely be the top choice

we mentioned in last year's feature article in synthetic fiber insulation recently.

One is the trend for active insulation, which provides moderate warmth while also increasing breathability and quick-drying properties, allowing you to wear it all day, whether you're standing still or moving, without having to take it off. The other is the trend for pseudo-down winter jackets that are extremely light, have excellent heat retention, and have insulation and recovery properties that approach those of down

Taking these major trends into consideration, we've narrowed down this season's most noteworthy models from among the many brands released, tested them in the field, and compared them from various perspectives. Here is our first comparative review of synthetic insulation jackets in about two years

table of contents

• About the items tested this time
• Test Results & Spec Comparison Table
• Impressions of each model
• summary

Regarding the synthetic insulations compared this time:

Originally, the purpose of this type of clothing was to keep warm, and it wasn't required to do anything more than put it on when you were staying still to keep out the cold, so I remember that there weren't that many options available. However, thanks to technological breakthroughs in recent years, countless models with different features depending on the purpose and season have now been released. It's impossible to cover them all, but this time I wanted to try out as many models as possible with as many different aims as possible and determine which one is best suited to mountain climbing in autumn, winter, and spring, so I narrowed down the candidate models for comparison based on the following criteria

• 100% synthetic fiber (hybrid models with down are not included)
• The amount of padding is enough to function as a mid-layer in the harsh winter or as an outer layer when snow remains (extremely bulky models intended primarily for outerwear are excluded)
• Choose from a wide range of models, primarily for mountain climbing, that offer simple "cold weather" functionality, as well as active insulation models that don't get stuffy even when you're active

From there, I chose the newest models, models I like the look of, and models that didn't suit my body type well after trying them on, and after much deliberation, these eight synthetic insulation items (mid-layer or cold weather gear) were finally selected as this season's top model candidates (the names of the synthetic insulation are in parentheses). I know I'm always biased, but that's just part of the charm

• MILLET K Belay Hoodie (Polartec Power Fill)
• MONTANE Icarus Jacket (PrimaLoft ThermoPlume)
• Mountain Hardwear Core Strata Jacket (PrimaLoft Gold Active)
• NORRONA lyngen Alpha90 Raw Jacket (Polartec Alpha Direct)
• Patagonia Micro Puff Hoody (Plumafill)
• Rab Alpha Flash Jacket (Polartec Alpha Direct)
• THE NORTH FACE RED POINT VERY LIGHT JACKET (THERMOBALL™ PRO)
• THE NORTH FACE Ventrix Hoodie (*The 19SS model is the WPB Ventrix Hoodie. Ventrix)

Until last year, I was blown away by the ease of use of products using Polartec Alpha Polartec Power Fill , PrimaLoft Gold Active , THERMOBALL™ PRO , and I'm personally trying many of these products for the first time, so I'm hoping they will exceed my expectations in a good way.

Test environment and evaluation criteria

The test period was from November 2018 to March 2019 in the winter in the mountains of the Kanto-Joshinetsu region, and the jacket was used for hiking, backcountry skiing, and as everyday wear. The following five points were used as indicators for evaluation criteria

• Heat retention: The most important feature for a mid-layer in autumn and winter. No matter how high-performance a jacket is, if it doesn't have enough heat retention, it will be difficult to wear
• Comfort: Feeling on the skin, ease of wearing due to silhouette and cutting, fit of sleeves, hem, hood, etc. No matter how warm it is, if it's uncomfortable, you won't want to wear it every day
• Ease of movement: It may be one thing if it's simply used as cold weather clothing, but in this comparison of synthetic fiber insulations, which are also intended for use as activewear, you'll also want comfort even while moving
• Resistance to sweating: If you plan to wear it while on the move, comfort when you sweat is also important. Ideally, it's best to have clothing that can constantly regulate the temperature inside the garment to an appropriate level in all situations, whether you're standing still, moving, or even wet
• Weather resistance: How much protection is provided against the outside temperature and environment. This mainly refers to wind resistance and water repellency. Of course, these are often in a trade-off with breathability, and some models deliberately forgo this functionality, so it's not necessarily true that a jacket lacking this feature is no good
• Weight: Lightness is essential for tough mountain climbing, and synthetic fiber padding is becoming increasingly light these days
• Storage: In the harsh winter, it's common to keep it on all the time, but in spring and autumn when there's still snow remaining, it's not uncommon to store it in your backpack. Recently, there has been an increase in packable designs that can be used as a storage bag by simply turning the pockets inside out

Test Results & Spec Comparison Table

If you find it difficult to see the table on the lightweight display for smartphones, click here.

comprehensive evaluation	AAA	AAA	AAA	AA	AA	AA	A	A
image
Item Name	Mountain Hardwear Core Strata Jacket	MILLET K Belay Hoodie	Rab Alpha Flash Jacket	THE NORTH FACE Ventrix Hoodie	THE NORTH FACE Red Point Very Light Jacket	NORRONA lyngen Alpha90 Raw Jacket	MONTANE Icarus Jacket	Patagonia Micro Puff Hoody
Reference price	25,920 yen	29,160 yen	18,360 yen	29,160 yen	30,240 yen	17,280 yen	25,920 yen	39,960 yen
Here is ◎	Heat retention Comfort Ease of movement Resistant to stuffiness	Heat retention weather resistance	Warm from the moment you put it on Ease of movement Resistant to stuffiness Lightness	Ease of movement Resistant to stuffiness Lightness	Heat retention per weight Lightweight and comfortable to wear	Ease of movement Resistant to stuffiness Lightness Storage capacity	Excellent heat retention weather resistance	Lightness Comfort weather resistance
Here is △	heavy	No stretch Slightly heavy	weather resistance Versatility	Slightly less heat retention	Ease of movement Resistant to stuffiness	Heat retention Comfort weather resistance	weight Ease of movement Resistant to stuffiness Storage capacity	Heat retention is just one step away Ease of movement Resistant to stuffiness
Heat retention	★★★★☆	★★★★★	★★★☆☆	★★☆☆☆	★★★★☆	★☆☆☆☆	★★★★★	★★★☆☆
Comfort	★★★★☆	★★★★☆	★★★★☆	★★★☆☆	★★★★★	★★☆☆☆	★★★★☆	★★★★☆
Ease of movement	★★★★☆	★★☆☆☆	★★★★★	★★★★☆	★★★☆☆	★★★★★	★★☆☆☆	★★☆☆☆
Resistant to stuffiness	★★★☆☆	★★☆☆☆	★★★★★	★★★★☆	★★☆☆☆	★★★★★	★☆☆☆☆	★☆☆☆☆
weather resistance	★★★☆☆	★★★★★	★☆☆☆☆	★★☆☆☆	★★★☆☆	★☆☆☆☆	★★★★★	★★★★☆
weight	★☆☆☆☆	★★☆☆☆	★★★★☆	★★★☆☆	★★★★☆	★★★★★	★☆☆☆☆	★★★☆☆
Storage capacity	★★★☆☆	★★★☆☆	★★★★☆	★★★☆☆	★★★★☆	★★★★★	★★☆☆☆	★★★☆☆
Specifications
Filling material	PrimaLoft Gold Active	Polartec Power Fill	Polartec Alpha Direct	Ventrix	THERMOBALL™ PRO	Polartec Alpha Direct	PrimaLoft ThermoPlume	Plumafil
Actual weight (g)	439(S)	404(S)	242(S)	278(M)	213(M)	176(S)	539(S)	272(S)
pocket	left and right chest	left and right Innerwear	chest	left and right Innerwear	left and right	chest	left and right chest	left and right Inner left and right
Packable	○	×	×	○	○	×	×	○

Impressions of each model

High-level in many aspects. The most versatile
Mountain Hardwear Core Strata Jacket,

Here is ◎

• Heat retention
• Comfort
• Ease of movement
• Resistant to stuffiness

Here is △

• weight

The fabric has a high degree of stretch, which is hard to imagine from its appearance

PrimaLoft Gold Active , a breathable insulation material developed by PrimaLoft, as its padding . First of all, I was surprised at how well it retained heat compared to other brands' cold weather gear that boasts breathability. The neck area is thick, so even though this model isn't a hoodie, cold air doesn't escape. Despite the tight silhouette that fills in any gaps, the exquisite three-dimensional cut prevents the hem from riding up when you raise your arms, and the four-way stretch and moderate recovery make it very easy to move around in.

The breathability of the padding isn't outstanding, but it doesn't make you feel stuffy while you're out and about. This model truly embodies the concept of "wearable all day." I never found myself shivering while packing down my tent in the winter mountains first thing in the morning, nor did I ever feel the need to take it off while hiking up the mountain. It also has some neat little touches, like a stylishly designed front zipper and packable design that can be stored in a chest pocket. However, the weight was something I found bothersome compared to other paddings, both when I measured it and when I wore it

The MILLET K Belay Hoodie offers a great balance of high insulation, weather resistance, and moderate sweat management, perfect for the harsh winter months.

Here is ◎

• Heat retention
• weather resistance

Here is △

• No stretch
• Slightly heavy

The heat retention per weight was quite high, and it was sufficient to use as cold weather clothing when stationary

Polartec Power Fill , the latest insulation introduced for the first time this season, is its high insulation performance, achieved through a unique process that creates fibers rich in air pockets. The soft, fluffy feel and bouncy, high volume and resilience are obvious when you hold it in your hand, making it extremely comfortable to wear. The weight is unnoticeable, and it feels lighter than its label suggests. This jacket, packed with ample padding, boasts some of the best warmth of the items on offer this season, and the outer fabric is windproof and water-repellent, making it a highly functional outer layer.

As this is a belay jacket, the pockets are positioned so that they do not interfere with the harness, and the adjustable hood and other features are designed to accommodate helmet use, which speak to the concept of this model

On the other hand, because it's not stretchy, it doesn't offer the breathable insulation you'd expect to wear all day. It does have some sweat-wicking properties, but because it has a large amount of padding, you might only feel the benefits in extremely cold temperatures. Still, it's safe to say that this is the most reliable model of its kind as a temporary mid-layer for cold weather in the harsh winter

The Rab Alpha Flash Jacket is a perfect mid-layer, offering exceptional warmth, breathability, and quick drying.

Here is ◎

• Warm from the moment you put it on
• Ease of movement
• Resistant to stuffiness
• Lightness

Here is △

• weather resistance
• Versatility

It combines high levels of heat retention, breathability, and quick-drying properties, so once you put it on, there's no need to take it off

Polartec Alpha is a high-performance insulating material developed for US military special forces. Its defining feature is that it combines two opposing functions at a high level: warmth, necessary for keeping out the cold, with breathability, quick-drying properties, and light weight, all of which are necessary for comfort while on the move. This model, with its exposed padding and stretch panels connecting the underarms and sleeves, makes the most of the new material's features.

The brushed padding creates a gentle warmth from the moment you put it on, creating a layer of dead air between the top and bottom layers. It's even more efficient than fleece. The stretch panels on the sides mean no stress when moving around. It also excelled in its sweat-wicking capabilities in this comparison. And that's to be expected, since the sweat it absorbs is simply dispersed without any sort of filter

Overall, this jacket performs best as a mid-layer under a shell, but it does let in a lot of air, so it's best used as an outer layer unless you're too hot and want to cool down, and you should always wear it with a jacket

The North Face Ventrix Hoodie: A new benchmark in breathable insulation jackets

Here is ◎

• Ease of movement
• Resistant to stuffiness
• Lightness

Here is △

• Slightly less heat retention

The air holes arranged in a grid across the entire lining further enhance the already high breathability

The North Face's proprietary Ventrix mechanism: it has stretchy, flat padding with slits that open and close in response to body movement, allowing air to pass through when you're active and trapping it in when you're still. The lining is also perforated with countless holes that efficiently disperse moisture from sweat, making it far less stuffy than other jackets with a lining.

The fabric has a smooth, dry feel and is extremely durable. The four-way stretch allows for excellent mobility, making this a truly breathable, insulated jacket

However, personally, I think it would have been better if it had a little more padding (warmth) when considering it as a jacket to wear throughout the winter. In this regard, I feel like last season's model had more padding, but this year's model seems to be more focused on being lighter. On the other hand, it seems like it would be perfect for the current season when there is still snow remaining

The North Face Red Point Very Light Jacket offers incredible warmth despite its light weight. Perfect for autumn and spring mountain climbing.

The North Face Men's Red Point Very Light Jacket, NY81805, Urban Navy, Size L (equivalent to Japanese size L)

created by Rinker

THE NORTH FACE

• Amazon
• Rakuten Market
• Yahoo Shopping

Here is ◎

• Heat retention per weight
• Lightweight and comfortable to wear

Here is △

• Ease of movement
• Resistant to stuffiness

From the outside, the amount of padding seems modest, but its heat retention is impressive

Perhaps the biggest surprise was THERMOBALL™ PRO . It weighs just 176g without the hood, and you can tell it's light the moment you put it on. When it's this light, it's comfortable to wear. The slightly uneven texture of the fabric is also nice.

But what surprised me wasn't its lightness, but its incredible heat retention, which was completely unexpected given its lightness. The filling, made of small ball-shaped fiber bundles kneaded with aerogel, a "gel-like air" with low thermal conductivity, transferred heat in a way that is unimaginable with ordinary flat-shaped filling, to the point that I was fooled into thinking, "Is this really generating heat?"

Unfortunately, the amount of padding is so small that the insulation is limited, making it a little insufficient for serious winter mountaineering. It's a shame, especially since the underarms are made of stretch fabric for ease of movement. It's perfect for the upcoming snow season and late autumn mountaineering

The NORRONA lyngen Alpha90 Raw Jacket is an essential mid-layer for spring and autumn mountain climbing.

Here is ◎

• Ease of movement
• Resistant to stuffiness
• Lightness
• Storage capacity

Here is △

• Heat retention
• Comfort
• weather resistance

The precision of the cut that adheres to the body line remains the same. It will be very useful for mountain climbing in spring and autumn

similar to aforementioned Rab a hybrid of Polartec Alpha Direct Alpha material is slightly thinner and only in the upper part, while the lower part is made of a thin fleece material, so it can be said that it has less heat retention. For this reason, even when wearing it as a mid-layer in full winter, it was not warm enough.

However, it's surprisingly lighter, easier to move in, and less stuffy, making it perfect for the upcoming snow season. The tight silhouette fits perfectly over a base layer, keeping your body temperature and humidity constant—neither too hot nor too cold. It's also comfortable to wear without a jacket when the warm winds start to blow

Down-like look and outstanding heat retention. A winter outerwear perfect for everyday use

MONTANE Icarus Jacket

Here is ◎

• Excellent heat retention
• weather resistance

Here is △

• weight
• Ease of movement
• Resistant to stuffiness
• Storage capacity

The baffle structure is the same as that of a down jacket, combining warmth and design

PrimaLoft ThermoPlume a fiber bundle so light you can blow it away with just your breath, and features a windproof and water-repellent PERTEX QUANTUM outer layer. Its high resilience, similar to down, and sophisticated quilting make it virtually indistinguishable from the outside, even though it's a synthetic jacket. I've been using it since last year, and its high heat retention, easy washability, and stylish design have made it a very useful everyday outer jacket.

However, since it is primarily intended as a down jacket, you can't expect much from it, such as stretch or resistance to stuffiness. While it can certainly be used outdoors, it's not as warm-weight-wise as the Millet K Belay Hoody , which also boasts warmth, wind resistance, and water repellency. (It's much heavier, too.) I found it difficult to carry or wear on serious mountain trips. It's also a bit of a pain to even out the padding after washing and drying.

However, the padding itself will continue to evolve until it reaches the same functionality as down, so I look forward to seeing more of it in the future

, the Patagonia Micro Puff Hoody would be an excellent winter outerwear.

Micro Puff Hoody

Patagonia

Here is ◎

• Lightness
• Comfort
• weather resistance

Here is △

• Heat retention is just one step away
• Ease of movement
• Resistant to stuffiness

In addition to the sophisticated baffle design, the stylish cut follows the contours of your body and the hood fits perfectly

Patagonia's much-hyped Micro Puff Hoody is a lightweight insulation jacket filled with their proprietary lightweight and highly resilient PlumaFill material. While the warmth per weight was certainly impressive, the sheer volume of padding meant it didn't offer enough warmth for serious winter conditions. The three-dimensional cut is impressive, providing a tight yet comfortable fit, and the hood fits perfectly. Since this is also intended as a pseudo-down jacket, you can't expect it to be comfortable to wear while moving around, but with just a little more warmth, it would have been a versatile model you'd want to wear every day, from everyday winter wear to outdoor activities. We're looking forward to seeing the Micro Puff Hoody with even more padding next season

summary

After trying out a variety of insulation jackets during the test, I learned that not only do the properties of the padding have various strengths and weaknesses, but the thickness (amount of padding) also determines the best way to use them. In terms of overall strength, versatility across seasons, uses, and functionality, I felt that Mountain Hardwear Rab , NORRONA, and MILLET all stand out when narrowed down to specific seasons and uses. Ultimately, only you can decide which is best for you.

When searching for the perfect piece to suit your needs and style, remember these ratings and use them as a reference

   

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