Review: A peek inside Mont-Bell's latest sleeping bag, the Seamless Dry Down Hugger 900, and witness the moment the impossible became possible

It's already been talked about everywhere, but for the 2020 season, Mont-Bell , has finally released the new sleeping bag, the Seamless Dry Down Hugger and I was able to get my hands on it straight away.

Ever since I first saw this sleeping bag at the trade show, I've been waiting for today, trying to hold back the urge to say it out loud. And it's no wonder, this sleeping bag is an amazing new product that has made major advances through innovation in what we've long taken for granted when it comes to down sleeping bags, or in other words, what we thought was "impossible to change." I'll be introducing it in detail, providing an actual review, explaining what makes it so great, how it's evolved, and, in my excitement, boldly dissecting the inside

Seamless Dry Down Hugger 900 (#3)

Mont-Bell 's Seamless Dry Down Hugger is a sleeping bag that revolutionizes the world of sleeping bags with its completely new construction. It successfully eliminates the bulkheads that keep the filling in place, a technical challenge in previous down sleeping bags. By minimizing seams, it achieves superior insulation and bulkiness while maintaining a lightweight design. Furthermore, the bag's completely new construction allows for the addition of a variety of safety and comfort features, including a waterproof and breathable GORE-TEX outer fabric, resulting in a sleeping bag that is both more comfortable and more functional than ever before.

the Seamless Dry Down Hugger which has a waterproof and breathable outer shell the Seamless Down Hugger, which has a nylon fabric that is not waterproof or breathable . The down filling is made with the highest quality 900FP down, and you can choose from #1, #2, #3, and #5 depending on the amount (only #3 and #5 are available for the Dry).

Recommended points

• Lightweight, waterproof and breathable, yet highly insulating
• Comfortable fit that doesn't restrict movement

Points of interest

• Hard to compress when storing
• High price

Main specifications and evaluation

What's so great about it?

First of all, what's so great about this seamless down hugger?

In conventional down sleeping bags, the inside and outside of the fabric are sewn together to create partitions, creating many small chambers and ensuring an even distribution of the filling. This prevents the creation of so-called "cold spots," or areas where the filling becomes thin, but confining the down to small chambers surrounded by partitions limits the down's high thermal insulation performance, which only comes into play when it expands, and also causes heat to escape through the seams themselves. Of course, the weight of the partition fabric and thread cannot be ignored

The Seams Down Hugger breaks new ground in sleeping bags by eliminating the bulkhead wall, something no other manufacturer had been able to do before

Until now, down has been kept uniformly distributed by confining it in separate compartments separated by partitions, the Spider Baffle System , a completely different method is used to distribute it evenly. This system spider yarn, which is strung throughout the inside of the sleeping bag, and entangles the down in it, keeping a certain amount of down in place without the need for partitions. Is there any greater game changer than this?

No bulkheads make it "lighter yet warmer": Its surprising internal structure

It's easy to say. If every manufacturer could turn their idea into reality, they would do it. The problem is, "How do they entangle the down in the thread? How are the threads spread throughout?" and so on, and so on. I was so curious about it that I decided to do something outrageous that I had never done before. I decided to actually cut it open with scissors and take a look inside. Kids, don't try this at home!

I decided to take a chance and cut the lining with scissors to see what was inside

Taking a look inside, we can see that it is filled with plenty of fluffy down. This down boasts extremely high recovery power of 900FP and is ultra-high quality "EX Down" with large, dense down balls

When you look inside, you'll see that it's stuffed to the brim with down

Since there is no partition, a large amount of down spills out from inside (when I opened it and looked inside, a considerable amount of down was blown away by the wind, tears)

Since there is no partition, a large amount of down spills out

Then, after digging around inside, I found a thread with down tangled in it! This is spider yarn

There it is, spider yarn. The down is tightly intertwined

I selected just one strand and took it out. A lot of down was entangled in one thread, making it quite voluminous

If you take out just one strand, you can see that the down is well tangled

The spider yarns were not individually but in groups of several, which were then entangled and secured in elastic threads sewn into the lining. By entangling several strands together, the down also became entangled between the individual spider yarns, and it is thought that a considerable amount of down could be efficiently secured in place with only a small number of threads

Several strands of spider yarn are bundled together and then wrapped around the elastic thread on the lining to secure it in place. That's a very well thought out idea..

By weaving countless bundles of spider yarn into a mesh-like pattern inside the sleeping bag, they have succeeded in keeping a certain amount of down in place without the need for partitions

Except for the inside, spider yarn is strung in all directions

Thanks to the spider baffle system using this spider yarn, there are no cold spots caused by down escaping from areas where weight is placed, so warmth is maintained evenly. However, not all of the down is tangled in the yarn. The untangled down can move around to some extent inside the sleeping bag, so this loose area allows you to adjust the distribution to suit the temperature and your preferred sleeping comfort

Because Spider Yarn is sewn into the inside of the sleeping bag, no seams are needed on the outer fabric, eliminating heat loss through the seams and providing greater warmth for the same weight

The outer fabric is truly seamless, making you wonder if it's really a sleeping bag

Waterproof and breathable function made possible by eliminating the bulkhead

The improved insulation performance of the Spider Baffle System also means a lighter sleeping bag. However, Mont-Bell has not simply made the sleeping bag lighter, but has taken full advantage of the lack of seams on the surface and applied waterproof and breathable GORE-TEX to the outer layer, creating a dream specification. This means that even without a sleeping bag cover, your down sleeping bag will always stay dry

Detailed Review

It's completely different from any other sleeping bag out there

At first glance, you might think, "What is this? Is it a sleeping bag?" Since it has (almost) no seams, it overturns the conventional concept of a sleeping bag

There are almost no seams on the surface, so it seems like it would be hard to tell what it is to someone who doesn't know

The inside of the bag has the same seams as the traditional DownHugger, and the spider yarn is woven into these seams

The Down Hugger Half Length is on the left, and the Seamless Dry Down Hugger is on the right. Both have the same interior

The hood has a slightly stretchy drawcord that can be tightened around the face

The hood is simple and can be tightened with a drawstring

There is a tube-like structure filled with down under the neck to fill any gaps and keep you warm

It's hard to tell from the photo, but the amount of down around the neck has been increased

Waterproof and breathable material

The outer material is GORE-TEX Infinium. Although it is the same GORE-TEX, Infinium's main purpose is not waterproofing like that used in jackets, but rather keeping you as dry as possible, that is, its main focus is breathability and comfort. In the case of sleeping bags, they are rarely used in environments where they are directly exposed to rain, and all that is needed is to isolate them from the outside air and release any moisture that has accumulated inside the bag, so using Infinium was a natural choice

The outer material is made of reliable GORE-TEX

You can see that the seams of the GORE-TEX outer fabric are securely taped behind the seams

The seams of the outer fabric are reinforced with seam tape for waterproofing

By the way, here's what the seam tape looks like from the inside. You can see that it's well reinforced. The inner fabric feels smooth to the touch, making it less likely for the down to cling to it

The seam tape on the inside of the outer fabric

The lining is made of Mont-Bell's proprietary ultra-lightweight shell, 7D Ballistic Airlite. The outer fabric is seamless as the name suggests, but the inner Ballistic Airlite side is sewn with elastic thread to secure the spider yarn and for super spiral stretch

The lining is sewn with elastic thread to hold the spider yarn in place and to give it flexibility

Unlike the Seamless Down Hugger, which does not use GORE-TEX, the zipper is short at 80cm, contributing to its lightness. Of course, it also uses a waterproof Aquatect zipper, which improves waterproofing

The zipper is short, 80cm long, and uses a waterproof YKK zipper

If you look at the zipper from inside the sleeping bag, you will see that there is a flap covering the zipper to prevent cold air from getting in. This flap is not flimsy, but is tightly filled with down

There is a flap behind the zipper to prevent cold air from entering

It is extremely lightweight, weighing just 523g. Compared to the same Montbell #3 sleeping bag, the Seamless Down Hugger 900 #3, which does not use GORE-TEX, weighs 494g, while the regular Down Hugger 800 #3 weighs 573g

The included accessories are a regular stuff sack (24g) and a mesh fabric storage bag (70g). This storage bag can be used for storing the bag when not in use for a long period of time, and can also be used as a laundry net for washing at home. The stuff sack has a trapezoidal shape with a large opening for easy storage

On the left is the laundry/storage bag, and on the right is the stuff sack

It comes with a tag with washing instructions so that it can be easily washed at home

The bag has instructions for how to wash it at home

Actual impressions after using it

First of all, when you get inside, you'll be surprised at how airtight it is. Because it's difficult for air to escape, it quickly inflates to its fullest. As expected, the outer fabric has no traditional seams, which makes it difficult for air to escape, and it's clear that it's quite airtight. This means that the heat from your body is firmly trapped in the down inside the sleeping bag, keeping you warm

And because there are no bulkheads, the way the down expands is quite amazing. This is the power of 900FP EX down... Even if you let the air out, it will expand naturally as soon as you leave it. It's amazing how limited the down in sleeping bags has been up until now

If you lay it flat, it will expand and become fluffy as it collects air

Thanks to this, you can enjoy the fluffy feeling when you go to bed and sleep very comfortably. It's amazing how much of a difference removing the bulkhead makes

However, due to its airtightness and high expandability, it is quite difficult to pack it up small, and it is a struggle to store it in a stuff sack

When you try to roll it up, it expands so much that it's difficult to store

Once the air is released, the amount of down is reduced, making it compact when stored

The storage size is very compact

As you'd expect from GORE-TEX, the waterproofing is excellent. I laid it flat and poured water over it for about 30 minutes, but no water seeped inside. I don't think anyone would use it in the rain, but since it's the same as having a GORE-TEX cover as standard, I no longer have to worry about condensation when using it in cold climates or when using it with simple equipment like a tent. This is a great advantage, especially in terms of weight and volume reduction due to not needing to carry a sleeping bag cover

As expected from GORE-TEX, there is no need to worry about waterproofing

The advantages of Mont-Bell sleeping bags are preserved even in seamless bags

Even though the outer layer is GORE-TEX, the Super Spiral Stretch is still there, allowing me to sit cross-legged comfortably. Some people choose Mont-Bell sleeping bags because of this Super Spiral Stretch, which is such a good design, so the fact that it's still there is a big plus

You can sit cross-legged as usual

I have a lot of confidence in Mont-Bell's temperature settings, so I feel confident about the warmth. Currently, only the #3 and #5 Seamless Dry Down Hugger sleeping bags use GORE-TEX for the outer layer, but since they seem more useful in winter mountains, #1 and EXP sleeping bags will likely be released in early autumn 

summary

A revolutionary sleeping bag has just arrived. It's a breakthrough, a giant step forward in what was once thought to be a near-perfect sleeping bag, thanks to new technology. The Seamless Dry Down Hugger eliminates the bulkhead, which was previously thought to be essential to the design, and takes the sleeping bag to a whole new level

This technology has made it possible to eliminate surface seams, which has brought about major benefits. The improved warmth has allowed the total amount of down to be reduced, making the jacket lighter and more compact. It has also made it possible to use waterproof and breathable materials for the outer layer. These two points alone offer enormous benefits, and will be applicable to users of a wide range of activities. In particular, those who take on more demanding and extreme conditions will be able to enjoy unprecedented benefits. I'm sure there were many who thought, "That's it! This is the kind of thing I've been wanting!" and that their imagination has now become a reality

However, the Seamless Dry Down Hugger (unusually for Mont-Bell) is not yet a product that should be discussed from the perspective of cost performance. Even conventional sleeping bags are certainly well-made with intricate design, and are certainly satisfying products. In that sense, I doubt that beginners will be happy with this sleeping bag. Rather, I feel that it is an item that can only be recommended to those who understand the appeal of this new technology and feel the need for the powerful benefits that can only be obtained with this model

Let's hope that the emergence of this sleeping bag will inspire other manufacturers to develop more, bringing a breath of fresh air not only to sleeping bags but to other outdoor gear as well!

   

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