Comparison Review: Summer Sleeping Bags What is the abilities of Montbell's latest high-tech sleeping bags? Comparing it with popular domestic models

Of the many mountain tools, many people have probably had the trouble choosing a sleeping bag (or sleeping bag). There are many areas where you won't know what to expect until you try it out, such as the compatible temperature range, quality of the material, weight, portability, and usability, so it can be quite difficult to choose the best one.

When climbing mountains in summer, the temperature difference between the ground and the summit is so extreme that it is often colder in the mountains than you imagined, so not only does not sleep comfortably, but in the worst case scenario, there is even a risk of hypothermia. As it is an expensive and important tool, you should gather information carefully when it comes to choosing a sleeping bag without compromising.

And, this season, mont-bell has announced a new innovative product. reviewed this high-end model, the Seamless Dry Down Hugger 900, on our website , and got a glimpse into its amazing evolution and capabilities.

So this time, we would like to compare popular summer sleeping bag models, including new models equipped with Montbell's innovative technology. To be honest, did you laugh when you compare it to Iska and Nanga, two major domestic brands that have been consistently popular due to their long-standing trust and track record? I'm sure there are many people who are very curious about it. It is difficult to make a perfect comparison and evaluation, as the actual questions and temperature ranges do not match perfectly, but I would like to carefully report on the differences, including these, and the key points to consider when choosing.

Sleeping bags compared this time

The sleeping bags we compared this time are classic models from the summer mountains. This is a so-called summer sleeping bag that is suitable for use for about a month, mainly in the midsummer of Honshu (July to mid-August). Although there may be slight differences between manufacturers, we assume that models have a limit-compatible temperature around 5°C to 0°C. The sleeping bags commonly used for mountain climbing are called mummy-shaped types, and the padding (heating material) is limited to down, which has a high heat retention per weight. However, since this category can be made relatively light, it can be used not only for down but also for synthetic fiber padding, and cheaper synthetic fiber sleeping bags may actually be an option. The three comparative models selected in this way are as follows:

• mont-bell seamless down hugger 900 #5
• ISUKA Air 280x
• NANGA Aurora Light 350 DX

Test environment

The test period is approximately two months from June to July 2020. It was used when climbing in Hokkaido, for camping, sleeping in the car, and for everyday sleeping. The lowest temperature at bedtime was around 8°C to 15°C.

Also, as for the test, I wore a base layer and a thin fleece on the upper body, while the lower body was a base layer and trekking pants.

Six indicators are set for evaluation items as follows. Naturally, evaluations and ratings are subjective and relative, based on the judgement of the tester.

1. Heat retention: How warm can you sleep even at low temperatures?
2. Weight: how light is it?
3. Comfort: How comfortable is it to sleep (soft to the touch and easy to move around in)
4. Storage: How compact can it be stored?
5. Strength to water, moisture, and wetting...How resistant to water and moisture, and how easily it dries?
6. Easy to use... how stress-free you can use it
7. Easy to care for... Can it be used for a long time?

Test results and spec comparison table

If you find it difficult to see the table because it is lightweight for smartphones, click here

Impressions of each model

mont-bell seamless down hugger 900 #5

A groundbreaking baffle structure that simultaneously reduces weight and improves heat retention

A popular sleeping bag that uses Montbell's new technology, the Spider Baffle System see here for ). The partition walls that were finely divided to prevent the down from being biased are removed, and instead, spider yarn intertwined with the down, is spread throughout the sleeping bag, allowing the entire sleeping bag to be evenly filled with padding. If you try to make the light through as shown in the photo below, you can see that down is certainly distributed throughout the sleeping bag without any bias, and that cold spots near the seams, which were impossible to prevent in previous sleeping bags, have been eliminated. I think this is something that even more impressive can be felt by experts with a long history of outdoor activities.

Addictive sleeping comfort

The highest-class down of 900FP is evenly arranged in a space with no bulkheads, meaning that there are no obstacles that limit the bulge. When I took my sleeping bag out of the storage bag, I was surprised at how it swelled up as if to say I had been waiting. Is the expression "fluffy sleeping comfort the most appropriate? The extremely thin fabric of 7 denier also provides the ultimate feel, and the comfortable sleeping experience, as if gently wrapped around the entire sleeping bag will make you addicted. #5 has this fluffy feel, so what happens when #1?

The manufacturer has not made the amount of down, but it is likely that they have made full use of the down performance of the 900FP and have reduced the amount of down to the very least. As for its heat retention, in the field with a minimum temperature of 8°C in late June, I was able to sleep well until morning without waking up due to the cold. There were no seams on the outer material, so airtightness was extremely high. Perhaps because of this, when I used it in an environment of 15°C it was hot and the zipper on my sleeping bag was unlocked. Well, the comfort temperature is 8°C, so it's only natural.

The familiar stretch system reduces cramped feeling.

The sleeping bag itself has a slim silhouette, but thanks to the super spiral stretch system, there was no sense of crampedness at all (photo below). Rather, it fits firmly to the body, resulting in no dead space and contributes to improving heat retention. The warmth of the sleeping bag is a very concern about the balance between weight and size, but I think this model is a very lightweight, compact, and warm item that I can confidently say.

You can't expect it to get wet

The outer material of the Seamless Dry Down Hugger 900 (#3 #5) also equipped with a Spider Baffle System uses GORE-TEX, which has waterproof and breathable properties, but the outer material of the Seamless Down Hugger is made of ballistic air light nylon material and does not have moisture permeability. As I will explain later, unfortunately the water repellent performance was disappointing. The zipper that reduces biting is also not as smooth as you might expect from others, and this is also a slightly negative point.

Overall, the spider baffle system and the continued super spiral stretch system are combined with the sleeping bag, making it a perfect finish for its lightweight, compact and comfort. However, realistically speaking, it is honestly a concern that when compared to the Alpine Down Hager 800#5 from the same manufacturer, there is not much difference in temperature, weight, or storage size despite the price difference. Personally, I would rather choose this, but I think I would be happier if I added one more piece of Yukichi and bought the Seamless Dry Down Hugger 900#5

ISUKA Air 280x

High quality down and unique 3D structure ensure maximum heat retention while being lightweight.

ISUKA is a long-established sleeping bag brand that has been leading the Japanese mountaineering world for many years. The carefully crafted product production, which has been developed repeatedly through repeated testing, has earned the trust of many mountaineers.

The model used this time was the AIR 280X. This model is positioned as a summer-use item among the popular Air Series. The filling is made of 280g of the highest quality 800FP white goose down. At first glance, it may look simple, but if you look closely, it uses extremely advanced technology, such as the unique 3D structure efficiently positioning the amount of down in each area, changing the chest side to a box structure and the back where the weight is placed is a single structure, increasing heat retention efficiency and light weight.

The limit temperature is 2°C. However, when I used it in an environment with a minimum temperature of 8°C, it was a little cold and I ended up layering it, but when I used it at a minimum temperature of 12°C, I was able to sleep well until the morning. Looking at Iska's website, all that is published is the limit temperature of use. Moreover, unlike Montbell and Nanga, it is a unique standard, so when considering a comfortable operating temperature, it is said that it is best to consider it at a higher temperature of approximately 5 to 10°C than the limit of use. The way people feel the cold will differ from person to person, but for me, a plus 5°C is not enough, so I think it's safe to think of it as a plus 10°C.

An excellent student who is easy to use and deals with wetness.

The outer material is made of nylon 66, which is ultra-water-repellent. During the water-repellent test, the shower continued to show off a spectacular water-repellent performance. However, after 10 minutes, water gradually entered the down. As the water-repellent properties continued, I think it is safe to say that it is penetrated through the seams and zippers rather than penetrating from the outer material. Well, it is not used in a downpour, so it has specifications that can adequately handle a certain degree of condensation and wetting.

Overall, it can be said that this item has a balanced balance in all items, while eliminating unnecessary things.

NANGA Aurora Light 350 DX

Reliability with carefully selected high quality and lifetime warranty

We have a wonderful lifetime guarantee that makes use of the unique know-how we have gained from manufacturing by skilled craftsmen and producing them in our own factory. NANGA is a domestic sleeping bag brand that has been used in recent years due to its stylish design . This time we selected the Aurora Light 350DX Speaking of the Aurora series, it is one of the most popular flagship models of the brand, with the outer material made of Aurora Tex , which is said to prevent certain amounts of water from flooding even without a sleeping bag cover.

Nanga is also particular about the quality of the down, but the traditional mix of Hungary, French and Spanish made its name as white duck down, all of which are made from European down, all of which are unified with Spanish down. The reason is that Spain has a considerable level of waterfowl rearing environment, facilities and structure, allowing you to obtain high-quality feathers, resulting in less sagging, and feathers that will retain their loft even after long-term use. The Aurora Light 350DX uses 350g of 760FP Spanish Spanish duck down. As it is a high-quality down, the limit temperature is 0°C, which is probably a little too hot for a summer sleeping bag, but it also has a sense of security as it can handle sudden cold weather. When it's hot, you can open the zipper to let the heat go away.

Comfortable to the touch and comfortable sleeping experience

The first thing I noticed after using it was that the fabric on the inside is softer than the outer material and feels very comfortable to the touch. The outer material Aurolatex repels the bounces as expected, even when poured in water. It's safe because the down will not become slurp due to condensation. However, since it is a hard fabric, it produces a slightly crisp sound when it moves. It's not so good that you can't sleep, but I think it's a concern for people who are sensitive to sounds when turning over.

The deep hood and draft tubes located along the zipper ensure heat, which increases heat retention efficiency and gives you a sense of security. Looking at the silhouette, the torso is wide and doesn't feel cramped. This may be perfect for those with a sturdy body, but for those with a slim body, it may cause a bit more dead space. The feet are slim, the feet are loose and the down is sealed in a large amount of sealed down, so there was no particular cold.

Parts that are easy to use and satisfy you down to the smallest details

The zipper reduces biting and is a luminous type that can be easily seen even in the dark. These carefully thought out details are impressive. However, it is not that there is no biting at all, and there have been several times when it is bitten without being operated carefully.

Weight and portability trade-off between heat retention and water resistance

It weighs 750g, the heaviest of the three models. The storage size is also large. Is this an item that must be sacrificed since Aurolatex material is used? However, it uses a single quilt structure to reduce weight. I didn't notice this in this test, but the single quilt structure makes the down at the seams thinner, which makes it a bit of a concern about the cold air from the so-called cold spot (photo below).

It is excellent in terms of comfort and waterproofness, but when looking at the balance between weight ratio and heat retention, it may not be suitable for UL packing because it places emphasis on heat retention. However, given the good detail construction, comfort and the comprehensive after-sales service with a lifetime warranty, this is an attractive feature that is unique.

Detailed reviews of each item

Thermal insulation

Even summer sleeping bags are used in cold weather from night to early morning, or in changing weather, so it is risky to underestimate their heat retention. It is important to select a model with the temperature range that suits your usage environment.

This test was conducted under an environment where the temperature was roughly 8°C to 15°C at night. The temperature did not get colder than the limit temperature of the three models that have been announced, so it was not so cold that I couldn't sleep, but in my opinion, the warmest of the three models was definitely Nanga. The down used is the lowest level out of the three models, the 760 FP, but the amount of 350g included more than compensates for this, and the warmth was by far the most obvious difference.

Perhaps not only the amount of down, but also the nature of the Aurolatex fabric used for the outer material increases the insulation effect. However, although we were not able to tell from this test, it was a single quilt structure, so I was curious to see what would happen when the usage environment approached the limit temperature.

I didn't really feel that there was much difference between Montbell and Isca. If I had to say, Montbell was a little warmer. For Isca, the temperature is not displayed in accordance with European standards, so when comparing the author's experience, it is safe to assume that the comfortable temperature is around 10°C to 15°C.

The heat retention performance of Iska is overwhelmingly superior compared to a typical sleeping bag. And yet, I was surprised that Seamless Down Hugger

If you look inside the zipper, Montbell has a flap to prevent cold air from entering. The Nanga also has improved heat retention performance thanks to the draft tube filled with plenty of down.

Also, the hood sections of the three models were deep for the Montbell and Nanga, and the Iska had shallow hoods, so I was a little worried when it was cold.

weight

The weight of the sleeping bag is closely related to its heat retention performance. Normally, heat retention performance and weight are proportional. Unlike winter sleeping bags, this is for summer use, so you tend to focus on models that are lighter than heat retention, but even if you prioritize weight reduction and reduce heat retention too much, you may be unable to sleep well because you are cold. The balance here is very difficult to balance with sleeping bags. For mountaineers who want to reduce weight by just 1g, the most enjoyable thing is that they can use lighter and warmer sleeping bags.

The lightest of the three models this time is Montbell. The actual measured value is 420g, including the staff bag. Not only is it a weight figure, but also considering the weight ratio taking into account the heat retention performance, it can be said that this is a huge victory for Montbell.

The use of the Spider Baffle system eliminates the seams, and the fibers of the ballistic air lights used have been changed from the conventional 10dn to 7dn. Furthermore, 900FP/EX down is used to reduce the amount of down to the very last that the heat retention performance does not deteriorate, resulting in a spectacular weight reduction. This is the lightest model compared to the sleeping bags in the same temperature range that are available from Montbell. Certainly, when I first opened it, I was worried that it was too light, so it was putting too much weight on reducing the weight. What's surprising is that even if the waterproof version of this model a seamless dry down hugger , the total weight is still below 500g.

However, I am a little worried about durability. With the fibers being changed from 10dn to 7dn, I can feel the fabric being quite thin. Even when I held the fabric down with force when opening and closing the zipper, I carefully removed the fabric from the zipper so that it took quite a while. Although it is not possible to judge durability at this time, we need to look at it a little more carefully.

Nanga is the heaviest, perhaps because it uses 15dn Aurolatex. However, considering that 350g of down is enclosed in, and the sleeping bag cover is also used, I don't think it is a generally heavy sleeping bag.

Comfort and sleeping comfort

No matter how light and warm your sleeping bag is, if it is uncomfortable to sleep, it will not relieve fatigue and will affect your behavior the next day. Looking at the material on the inside of the sleeping bag, all of the sleeping bags were made of soft fabric and there was no discomfort to the touch. However, the other two models do not have the enveloping sleeping experience created by Montbell's Spider Baffle System and the 900FP down, making it a landslide victory for Montbell. It also comes with a super spiral stretch system, making it the perfect sleeping bag for people like me who have a bad sleeping position.

The Nanga is also relatively wide, so just like Montbell, I was able to hold my clothes inside the sleeping bag and also change clothes inside the sleeping bag. I don't feel any cramped feeling either. However, as mentioned above, the outer fabric is hard, so when it moves, it produces a crisp sound.

Iska cannot sniff in her sleeping bag and cannot move around in her sleeping bag as much as Montbell and Nanga. However, I didn't feel cramped, and I couldn't say it was uncomfortable to sleep on. Perhaps it didn't go well with the sleeping pads I use, but it was quite slippery when I turned over, so before I knew it, it was falling off the pads frequently, and it was a shame that I couldn't sleep very well. Of the three models, the Nanga was the most unslip and stable.

Storage size

This sleeping bag takes up a lot of space inside the backpack when packing, so the more compact it becomes, the more helpful it becomes.

All three models this time come with stuff sacks, and all are two-stage styles with double drawcords, making them compact enough for their weight. Looking at the stuff sack, Montbell uses a super spiral stretch system similar to that of the sleeping bag, so there was no stress when storing it. It's a bit of a relief, but it's helpful that you can roll it around or stretch it out sideways, and change it to your favorite shape when packing.

The Iska and Nanga are packed full when stored in a stuff sack, but the Montbell had enough room to make it more compact if you use a compression belt. Another great thing about Isca's stuff sack is made of Cordura material, which is durable.

Strength of wetting to water and moisture

To test the water repellent properties, we continued to pour water on each sleeping bag in the shower, and after 3, 5, and 10 minutes, we compared the water repellency of the outer material with the intrusion of water from the zipper. Furthermore, we investigated whether the sleeping bag is completely submerged in water and can be used when wet.

As a result, the most water-repellent performance was Nanga. Although the shower continued for 10 minutes, no water was allowed to enter the down. As expected of Auroratex, it doesn't require a sleeping bag cover. However, there was a small amount of water entering through the zipper. In fact, we have confirmed that water has penetrated through the zipper on all three models. This may be a challenge to overcome in your sleeping bag.

Even after submerging it in the water, the Nanga took the most time to get shaggy. This also shows that it is a model that is quite strong against water. Also, when used in an environment of 15°C, it was hot and the zipper on the foot was released, but it basically didn't get stuffy. This makes it a model with excellent moisture permeability and is said to be the best waterproof and breathable model.

The one that was disappointing was Montbell. Since there were no seams on the outer material, I was very hoping for its water-repellent properties, but after 5 minutes the down became damp and after 10 minutes the down became almost slurping due to the intrusion of water from the zipper. Even when submerged in the water, it was flooded the water the fastest. As for waterproof and breathable performance, it is believed that the seamless dry-down hugger, which uses Gore-Tex on the outer material, is overwhelmingly strong.

Convenience and ease of use

Zipper operation is important for sleeping bags. Sleeping bags, which frequently bite zippers in the field, take time to spend and are by no means an excellent sleeping bag.

All three models have specifications to reduce biting, but none of them did not biting at all. Here, I felt stressed because I had the least biting of Isca, and I was bitten by Montbell frequently. I'm worried that the fabric will tear because it's thin. All three models can be opened and closed from the foot, making it easy to adjust the temperature.

Nanga's luminous slider is very helpful when operating in the dark. Personally, I'm disappointed that the slider knobs are not flap-type like the Montbell and Isca.

Looking at the finer details, the Montbell has a folded-back opening at the top of the zipper, preventing the zipper from coming into contact with your face, which is a great treat.

Ease of maintenance

It is important to wash your sleeping bag thoroughly to last longer and extend its lifespan. You can wash your sleeping bag at home, but it cannot be washed like regular clothing. It is necessary to handle the feather carefully so that it does not wear out, such as washing, dehydration, drying, and other shaking. If you ask a professional to clean it, you will be able to save you time and be satisfied with the finished product, but there are probably many people who do it themselves because it is quite expensive.

This time I washed all three models at home. It was quite difficult, but washing the Montbell was the least burdensome. This is because there was no bias in the down after it was dry, which saved me a lot of effort. That's one of the strengths of the Spider Baffles system. Of course, it goes without saying that Nanga and Iska had to place the down evenly after drying.

summary

I was paying attention to the Montbell Seamless Down Hugger, but after examining it, I found that not all of the items were excellent. Although the results were consistent in terms of heat retention, weight, portableness, and sleeping comfort, we also found that there are still some items that cannot beat other models, such as weakness to wet and stuffiness, poor usability, and price. I think the priority items differ from person to person, but Montbell is for those who want to reduce weight, Nanga is for those who want to keep warm and have strength against water even if they are heavy, and Iska is balanced in all of the items, making it ideal for beginners. However, although I haven't included this comparison, I guess based on the excellent performance of Montbell's book, I think the Seamless Dry Down Hugger , which I put off in terms of price, is lightweight, highly insulating, while compensated for its ease of wetting, making it the best choice that currently has no shortcomings other than the price.

Unlike winter sleeping bags, which are most important in heat retention, summer sleeping bags differ in the types of summer sleeping bags that excel in each model. There are probably many areas that you won't know until you actually use them, but it is important to gather information carefully and choose a sleeping bag that suits your usage environment.

We hope this article will be helpful when choosing a summer sleeping bag.