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MontBell Plasma 1000 Down Jacket

rated 4 of 5 stars
photo: MontBell Plasma 1000 Down Jacket down insulated jacket

Extremely lightweight jacket for ultralight backpackers.


  • Extremely lightweight
  • Comfortable fabric
  • Decently warm


  • No pockets
  • No hood
  • No adjustment straps
  • No pit zips

I should start by saying that the Montbell Plasma 1000 is a new jacket for me. I purchased it a few weeks ago for ultra lightweight warmth while backpacking through New England this fall. In the brief while that I have owned it, I have been able to take it out a few times and get some initial impressions.

Fit:  The Plasma is a fairly slim fit jacket, as much as down can be "slim fit". It still looks puffy, but doesn't feel baggy at all. Overall, the fit of the Plasma 1000 is closer to a sweater than a jacket. The body is shorter than other down jackets I own, but is about on par with most sweaters I own. It is one of the few pieces of hiking clothing that I want to wear around normally.

The 1000 fill down has amazing loft, but it feels nice and sleek when you're wearing it. I really like the look and feel of this jacket. Best of all, the slim fit makes it easier to layer a rain jacket over the Plasma 1000 for added weather protection. My Outdoor Research Helium II (size large) fits perfectly over my Plasma 1000 (also size large).


Comfort:  The Plasma 1000 is extremely comfortable.  The down weighs almost nothing and the fabric itself is really soft.

Warmth:  This certainly isn't a winter coat, but it does a good job for three-season hikers seeking a lightweight additional layer. I have been wearing it every day for the past few weeks (including several day hikes and one nighttime hike) as a light fall jacket and have found it to be very warm.

Thus far, the coldest conditions I have tested would be 43°F with a 19 mph wind. I found that the jacket blocked the wind wonderfully and kept me nice and warm (I even had the zipper most of the way down while hiking). If you aren't moving, the wearable temperature does change a bit.

found it a bit chilly at 45°F (though still comfortable enough) while sitting on my porch and reading. However, I also found that this jacket does a great job of holding onto trapped heat. Once I moved around for a few minutes, things warmed right up and stayed there for quite a while.  

One nice thing about the cut of this jacket is that it fits perfectly under my Outdoor Research Helium II rain jacket. This combination could be used to give the Plasma 1000 a greater usable temperature range.

Materials:  The Plasma 1000 uses 1000 fill-power goose down and gossamer 7-denier nylon. What's important here is the 1000 fill goose down and the 7-denier nylon. The 1000 fill goose down is extremely high loft and thus provides lighter weight and better warmth.

This does come at a price (higher fill-power downs have to be harvested from mature broodstock geese during molting season as opposed to lower fill-power downs which are taken from younger geese which are harvested for consumption), but the difference is tangible the minute you pick up this jacket.  

My other primary down jacket uses 800 fill-power down (anything above 750 is deemed "excellent"). That jacket is already extremely light weight and soft, but it pales in comparison to the Plasma 1000.


A big part of the softness / comfort of the Plasma 1000 is the 7-denier nylon (specifically, 7D Ballistic Airlight rip-stop nylon).  With fibers 3/5 the diameter of a human hair, 7-denier nylon is an extremely lightweight nylon weave (25g / m^2) that is known to feel good against the skin.

Oddly enough, I was recently informed that, in addition to its use in camping equipment, 7-denier nylon is sometimes used in women's stockings. While this nylon does feel fantastic against the skin, I still have a hard time being completely comfortable with it. In my daily life, I tend to wear Arctic expedition parkas from companies like Canada Goose and Bergans.  This has more to do with my being a wimp in the cold than any actual expeditions, but one great benefit is that these types of coats are nearly indestructible. Their fabrics are thick enough that I could roll around in gravel without worry.  

The 7-denier nylon used in the Plasma 1000 is so lightweight that I find myself treating it with kid gloves for fear that I'll tear it. Montbell swears that, in addition to its weight, 7-denier nylon was chosen for being "durable enough to withstand the rigors of normal use for an insulated inner piece".

Design / Construction: This is a very purpose-built jacket. Everything about its design screams "ultra lightweight"! The 1000 fill down is as light as it gets. The 7-denier nylon is remarkably thin and lightweight.  Every single extravagance has been removed in the pursuit of lighter weight. This means no pit-zips, no draw strings, and no pockets. You do get elastic on the cuffs, but that's it.  

If you view the Plasma 1000 as a jacket, this seems a little extreme. However, if you see it the way an ultralight hiker does—as a lightweight fleece replacement / supplement—then it's more understandable. Even in daily life, I've found that I don't mind too much (given the temperature doesn't drop low enough that I want pockets) since I think of this garment as more of a zippered, down sweater than a jacket.

Montbell makes a point of pushing their "sewn-through-construction". This just means that all stitching goes all the way through both layers of fabric. To be honest, I don't think I have ever owned a down jacket that wasn't sewn-through construction.

Still, the Plasma-1000 does take a somewhat new approach. Most down jackets are sewn into compartments. These compartments keep the down from all migrating to one corner of the jacket and ending up like a lumpy old down quilt. However, all this thread adds up when you're aiming to make the lightest down jacket around.

What Montbell has done instead of the traditional horizontal or square compartments is to create a pattern similar to a simplified Greek key. This minimizes the amount of thread used while also ensuring down stays well distributed throughout the jacket.


Weight / Packability: To my knowledge, the Plasma 1000 is the lightest down jacket on the market at the moment. Their advertised weight is 4.8 oz. Obviously all manufacturer-advertised weights are for one size only. I'm not sure which size was used for this particular measurement, but my Large-sized Plasma 1000 comes in at 5.5oz including the stuff sack.  

I also found their advertising of the packed size to be slightly exaggerated. It's possible that this image was from an earlier model or that the jacket's size plays a role here as well. I have fairly large hands, but wasn't able to get my fingers around the packed jacket anywhere near what was depicted in the advertisement.

Even taking this into consideration, the Plasma 1000 is a remarkably packable down jacket. You can see its packed size and weight in the images below. Even when packed, there was still a fair amount of give. Given a smaller stuff sack, I might be able to make the manufacturer's claim of 3.9" x 5.5".


Source: bought it new
Price Paid: $269

Extremely lightweight down jacket that's warm with a few compromises.


  • Ultra-lightweight
  • Wind Resistance
  • Warmth
  • Packablility


  • Heavier than advertised
  • No pockets
  • No drawstrings
  • Ultra-lightweight fabric needs extra caution

Brent provided a great in-depth review. I thought I'd add a second opinion.

I had been eyeballing this jacket for not only casual use, but also for backpacking. As it's my first and only down jacket, I went for ultra-lightweight for backpacking. I asked for it for Christmas and Santa was good to me. I'm 5'10"/160 lbs and purchased a large version directly from Montbell.

Weight was one of my most important factors and this was the lightest (advertised) that I could find.  

Unfortunately, like Brent, my large version came in at 5.3oz with the stuff sack (144g + 5g) — 1/2oz. heavier than advertised but still (significantly) lighter than anything else that I'm aware of.

To achieve the ultra-lightweight Montbell had to make compromises vs. other down jackets that I was well aware of and happy to concede. The 7-denier fabric is hyper light, there are no pockets, there are no drawstrings, the zipper is a very lightweight zipper. In warm weather, I don't have pockets on my torso so I figure I'm not giving up much there. The sleeves are elastic and work well. The jacket's slim cut reduces the need for a drawstring at the waist and I don't miss it. The zipper works flawlessly.

I've had occasions to wear the jacket in temps in the high 20's with a biting wind and found the jacket very wind resistant and warm despite the sewn-trough construction. It seems Montbell's strategy with the unique baffling helps reduce "sewn-thru" cold spots and shifting of the down. After wearing the jacket while driving a few times, the down in the back area compressed. After a few shakes and hanging the jacket up, the down recovered nicely.  

My stuff sack is similar in size to Brent's. It could be stuffed smaller given a smaller sack. That's not a concern for me.

In summary, it's an awesome jacket if you're willing to live with the compromises. I'd give it five stars if the weight were as advertised.

Source: bought it new
Price Paid: $269

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Price Historic Range: $215.20-$269.00
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