Sea to Summit Spark / Spark Pro -1C Sleeping Bag Review: The highest standard of lightness and comfort are condensed into a simple form. Furthermore, the best value for money is hidden and honor student sleeping bag
Written by Yasushi Hisatomi
The long-awaited update for the 2024 season, the "Sea To Summit Spark" series of sleeping bags for mountaineering and hiking, which I've been my secret favorite for a while.
To get a comfortable sleep with a sleeping bag, an essential equipment for staying in a tent in the mountains, you need many factors, including warmth, lightness, comfort, convenience, and price, but in many cases, warmth and comfortable, heavier, and lightness makes it cold, cramped, and uncomfortable to sleep. In order to get through the gaps in this dilemma and keep each element in a high level of balance, not only needs cutting-edge technology, but also "sense" such as what to strip and what to leave and how far to keep.
After looking at various sleeping bags for a long time, the Sea To Summit Spark Series was the most efficient sleeping bag that would have put together the difficult balance and resulted in the most practical product. As Spark is the first major update in years, we can't help but look forward to it.
This time, I was able to try out the latest, more advanced "Spark -1C" and the newly released "Spark Pro -1C", so I'll give you a review of what I tried out when climbing a tent.
table of contents
- Sea to Summit Spark/Spark Pro -1C Main Features
- Detailed review
- It is surprisingly lightweight and compact for a full-length, full-size mummy type
- Top-class high-quality down that combines light weight and heat insulation (and is water-repellent).
- The extremely thin, lightweight, durable nylon fabric is lightweight and supple, and has an exquisite feel to the touch.
- Waterproof and moisture-permeable hood and footbox that prevents down from getting wet inside the tent
- The width is slightly wider than the previous model, and the standard size makes it more comfortable to sleep on.
- The improved zipper is designed to be less likely to bite, and is designed to be lighter and has a minimum length.
- "Pro" model with the highest quality down and zipper for improved breathability, suitable for a wider range of temperature ranges
- Summary: The attractive sleeping bag is light and heat insulation, making it even more comfortable, safe, and easy to use, making it even more comfortable and has a great quality for mountain sleeping bags.
Sea to Summit Spark/Spark Pro -1C Main Features
Sea to Summit's Spark series is a classic mummy-shaped sleeping bag that eliminates waste in the smallest detail and is the most lightweight and compact in its class. In addition to the high quality of 850+FP (professionals 950+FP), it also uses down padding with a water-repellent finish. The baffle structure combines different structures on the upper and lower body to prevent cold spots as much as possible, and the draft tube around the zipper provides efficient and high heat retention. It is not too light in weight, with a 10-denier nylon fabric and a short zipper, and has insulation that can withstand below freezing temperatures, yet is lighter than 500 grams with official weight (professionals 619g). The newly released "Spark Pro" this season allows flexible temperature control by introducing a sub zipper. It provides a comfortable sleeping experience under a wide range of temperatures. With its minimalist construction, the sparks keep you warm for a night of weight and performance-oriented hikers from spring to fall.
Favorite points
- It is surprisingly lightweight and compact for a full-length, full-size mummy type
- Very high quality 850FP (professional 950FP) and water-repellent finish, wet-resistant down
- The ultra-thin outer fabric is light and supple, and has an exquisite feel to the touch
- Waterproof and moisture-permeable hood and footbox that prevents down from getting wet inside the tent
- A skillful baffle construction and draft tube that is difficult to produce cold spots
- (Professional only) When it's hot, the zipper allows for a wide range of temperature control with feet and hands.
- (Professional only) The fully open zipper combines two sleeping bags to arrange for two people
- Many uses with few drawbacks
- A high-quality, high-performance sleeping bag of the same class, is an easy-to-take price
Interesting points
- The short zipper is hard to adjust the temperature when it gets hot and stuffy (normal)
- While many zippers are convenient, they can be complicated to operate, and the downsides to weight and flexibility cannot be ignored (professional)
Main Specifications and ratings
| Item name | Sea to Summit Spark -1C (Regular) | Sea to Summit Spark Pro -1C (Regular) |
|---|---|---|
| Adapted height | 185cm *Women's model also available | 185cm |
| Storage size | 13.5 x 19.5 x 34cm | 13.5 x 19.5 x 34cm |
| Fabric material |
|
|
| Insulation material | 850+ Premium Goose Ultra Dry Down (RDS certified) | 950+ Premium Goose Ultra Dry Down (RDS certified) |
| Official weight | 493g | 619g |
| Down weight | 265g | 310g |
| Official lower temperature | -1 ℃ (ISO23537) | -1 ℃ (ISO23537) |
| size | 155/135/102cm from top | 155/135/102cm from top |
| accessories |
|
|
| Outdoor Gearzine Review | ||
| Comfort | ★★★★★ | ★★★★★ |
| Thermal insulation | ★★★★☆ | ★★★★★ |
| weight | ★★★★☆ | ★★★☆☆ |
| Storageability | ★★★★☆ | ★★★☆☆ |
| Easy to use | ★★★★☆ | ★★★★☆ |
| Durability | ★★★☆☆ | ★★★☆☆ |
| Versatility | ★★★★☆ | ★★★★★ |
Detailed review
It is surprisingly lightweight and compact for a full-length, full-size mummy type
The Spark series has a "mummy-shaped" shape that is orthodox for a sleeping bag for mountain climbing. The padding is enclosed throughout, including the back and around the head. The length is also a regular size, up to 185cm tall, and it is quite generous, so it is unlikely that even the average Japanese person will find it cramped. Long sizes (up to 198cm) and women's models (up to 170cm without professionals) are also available for those who are tall and short.
And while they don't really care about reducing the weight, the fact that they are lighter and more compact than their competitor sleeping bags is a major attraction that continues to last for the rest of the day. The weight is 493g for sparks, and the specs can withstand below freezing, making it lighter than 500g, making it a very competitive weight. *The "pro" model is not that light for the Spark series due to the zipper that will be described later.
If you put the packing in the included storage stuff sack with compression function, the spark can be reduced to about the same height as a 500ml plastic bottle (photo below).
Reference to the size when packed. Spark Pro (left) wasn't that small, but Spark (right) was quite compressible.
Despite the orthodox construction and warm sleeping bags that are warm enough for three seasons, how can they be so light? The secret lies in the detailed selection and construction of materials that were carefully selected and made without compromising on both performance and lightness. Next, let's unravel it.
Top-class high-quality down that combines light weight and heat insulation (and is water-repellent).
The finest high quality downs, which were attractive since the first generation when the Spark series was first developed, are still alive and well this time.
In terms of "fill power (FP, height of bulk)," which indicates the insulation per weight (quality), down is said to be high quality at 600 or more, and the highest quality at 800 or more. The down used in Spark is sustainably sourced (RDS certified) and boasts a loft height of 850+ FP (professional 950+ FP). What's more, the feathers are made of a higher quality goose down with larger feathers. Even when looking at the market, it can be said that it has the highest level of lightness and insulation.
Moreover, this down is pre-water-repellent, making it less likely to get wet (hard to absorb moisture) than usual. Down will significantly lose its heat retention when wet, so its weakness to wetting is said to be a weakness of down (against synthetic fiber padding), and this water-repellent treatment protects the down from water vapor in the atmosphere, making it possible to accommodate tents in more harsh environments.
It is no exaggeration to say that the premium goose ultra dry down is the best, light, warm, and not easily wet, making it the strongest down at the moment.
Furthermore, some effort has been made to the structure and arrangement of the baffles (bulkwalls) packed with excellent padding.
The upper and lower bodies use different baffle structures, and the limited amount of down is being used to achieve maximum comfort.
The chest has a box structure (creating a more three-dimensional and wider space) to improve heat retention, and a baffle structure that is arranged vertically so that feathers do not become unbalanced even when rolling over (top left).
The lower half of the sleeping bag uses a crushed-stitched sown-through structure that emphasizes the balance between heat retention and breathability and light weight (sew the fabric through and stitches), and this one is arranged horizontally (right on the top photo). The body mapping design is tailored to this area, and the limited amount of padding is placed to provide maximum warmth and comfort.
The extremely thin, lightweight, durable nylon fabric is lightweight and supple, and has an exquisite feel to the touch.
The tightly woven 10 denier ultra-thin nylon fabric is light and supple to the touch.
The front and back of the main body are made of extremely thin nylon fabric, 10 denier. It is woven tightly and does not fall off, has a durable water-repellent finish, and is extremely thin and lightweight, without losing its durability.
I particularly like the silky silky-like feel of the liner fabric that touches the skin, and even with this comfort alone I would want to turn it into a normal sleeping bag for mountain hiking.
Waterproof and moisture-permeable hood and footbox that prevents down from getting wet inside the tent
The feet were shaped in three dimensions to match the shape of your feet (though this class of sleeping bags would not be a surprise), and the addition of unnecessary stress was reduced, while also packing sufficient padding to prevent coldness. Even more thankfully, the fabric around the feet and head is made of waterproof and breathable material, which is why this area, which often sticks to the side walls of the tent, is enhanced.
The feet (and head) are cut three-dimensionally to match the shape, and by placing waterproof and breathable fabric, water from entering through the walls of the tent.
The width is slightly wider than the previous model, and the standard size makes it more comfortable to sleep on.
The spark up to the previous model was by no means wide enough to be considered relaxed, but this time it was a little wider than the previous model, allowing you to relax in your sleeping bag more comfortably. The finest, warm feathers wrap around softly and gently (without tightness).
Compared to the previous model, the overall width has become slightly wider, and I almost no longer feel the feeling of crampedness that is common with lightweight models.
It is true that this has slightly increased the weight, but for me, who have bought a sleeping bag that is quite narrow and too cramped in the past due to lighter weight, I would like to welcome this increased comfort.
The improved zipper is designed to be less likely to bite, and is designed to be lighter and has a minimum length.
The zipper on the left side has evolved into a zipper with a guard to prevent the fabric from getting bitten, making it even easier to use (photo below).
Furthermore, it has a double zipper system that can be opened and closed from both the top and bottom, allowing you to adjust the ventilation by leaving only your left hand while the neck is closed (right of the photo below).
However, since it is designed to eliminate waste as much as possible, the spark has a short design that only reaches the waist (left of the photo below). This has a major advantage in terms of weight reduction, but it is inconvenient to avoid heat in hot seasons such as summer, so I don't think I'll ever think to take the Spark-1C to the low mountains in the middle of summer.
On the other hand, professionals can open the entire area, including their feet, so they can respond flexibly even when the temperature is higher (right on the photo below). Professionals are better at comfort over a wide range of temperatures.
The opening and closing range of the zipper differs significantly between Spark and Pro. The Spark Pro (right) can open the main zipper from above as shown in the photo, and if you open the zipper at your feet, it will open completely and can be used as a blanket.
Both Spark and Pro have a padded draft tube located on the back of the zipper to shut out the cold air.
"Pro" model with the highest quality down and zipper for improved breathability, suitable for a wider range of temperature ranges
As I mentioned a little earlier, the difference between Spark and Spark Pro is that it mainly uses lighter, warmer, 950+ down, and the other is that the main zipper on the sleeping bag is longer and a sub zipper (free flow zipper) is added for even more convenience and easier to regulate body temperatures at a wider range of temperatures.
Specifically, there are zippers on the left side of the main unit, as well as on the right side, and on the feet, and by opening them, you can bring out both your hands and feet from the sleeping bag, allowing you to sleep while cooling the ends (photo below).
Professionals are able to adjust the product so that you can sleep comfortably even when it's hot by sticking out both your hands and feet. The reason we use the finest class 950+FP down is to reduce the weight gain caused by this addition of zipper.
Plus, if you open all the zippers completely, you can also use it as a single blanket (photo below).
These zippers allow professionals to sleep in just the right amount of warmth by exposing their arms and legs or using them as quilts, not only in the cold early spring or early winter, but also in the middle of summer, making them comfortable to use, literally three seasons. Considering that normal sparks are more likely to be used in the middle of summer, this versatility is a significant advantage.
However, instead, the advantages of Spark Pro's "lightness" and "simple ease of use" that they have lost are never ignored. You can choose the most versatile for various seasons, scenes, and uses, or the high fit for the scene, although it may be narrowed down to the purpose, both of which are surely the high quality of the base, but it can be said that the decision is left to the user.
Summary: The attractive sleeping bag is light and heat insulation, making it even more comfortable, safe, and easy to use, making it even more comfortable and has a great quality for mountain sleeping bags.
The Spark series, which was originally attractive for its lightness and high insulation, has now been made more comfortable to sleep on (although it has slightly increased its weight), and the smallest details make it safer and easier to use, making it overall a lightweight sleeping bag. That's a big part of what I would like to appreciate, and it's still one of the three best climbing sleeping bags in my opinion.
The new Spark Pro has also expanded its use from traditionally lighter hiking-oriented applications to a wider range of seasons and activities, and I feel that this product will appeal to those who want a sleeping bag that can be used all year round, as it doesn't need to be as light as possible. In that sense, personally (in terms of mountain climbing style) I plan to use the traditional orthodox evolution "Spark -1C" for fast packing and stream climbing in the future.
This lightness (high insulation per weight) is not only ideal for speed hiking and fast packing. And the orthodox construction is completely fine for general mountain climbing or harsh mountaineering. The appeal of this sleeping bag is that it is generally easy to fit in a variety of ways.
And finally, I would like to emphasize this one. The amazing price should not be forgotten. It is so well-finished, highly functional and high quality, and although it is an overseas brand product, it is an incredibly cheap product. That said, the affordable prices up to this point will be until August, and be careful, as soon as the other-dimensional discount campaign at Lost Arrow, the import agency, ends, this low price may end.
If you only know Japanese sleeping bags, you should definitely try this sleeping bag and be surprised at how high quality it is. Please pick it up at the store this summer and check it out.
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