How to Choose Sleeping Bags for Backpacking
Sea to Summit Trek Tk II Sleeping Bag - Men's
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The Sea to Summit Trek Tk II is a lightweight, 3-season bag with a roomy semirectangular shape and high-loft water-resistant down insulation for excellent warmth and compressibility.
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Fill
650-fill duck down
Temperature Rating (F)
18 degrees (F)
- Insulated with 650-fill-power duck down for warmth, light weight and compressibility; Ultra-Dry Downâ„¢ water-repellent treatment protects down from moisture
- Ultra-Dry Down is a water-repellent polymer treatment applied to the 650-fill down; Ultra-Dry Down retains 60% more loft and absorbs 30% less moisture than untreated down
- With a European Norm (EN) lower-limit rating of 18°F, the Tk II bag will help keep you warm on spring, summer and fall backpacking trips
- Shell fabric is constructed of a high-density weave, 33-denier fabric treated with a durable water repellent (DWR) finish
- Shell material is highly vapor permeable and downproof
- Lining is a breathable, durable 40-denier nylon fabric with a soft touch
- Full-length side zipper and foot zipper allow bag to be converted from traditional sleeping bag to a duvet/down comforter
- Semirectangular shape provides more room than a mummy bag for a more comfortable sleeping bag while maintaining thermal efficiency
- Differentially cut inner layer is smaller than the outer layer to create a consistent thickness of insulation that precludes cold spots
- Oversize draft tube backing the 2-way zipper keeps the warmth in and the cold out; zipper is backed by stiff, antisnag tape for smooth operation
- Large interior security pocket is great for stowing a few essentials, alleviating middle-of-the-night fumbling
- Baffle construction allows the goose down to remain fully lofted and keeps it from shifting
- Sea to Summit Trek Tk II bag comes with a Ultra-Sil® compression sack and a mesh storage sack that can be used for drying the sleeping bag in a dryer
Imported.
Temperature ratings are intended as a guideline to help you compare products, rather than a guarantee of warmth, since many different factors contribute to your comfort while you sleep. Backpacking bags are typically rated for temperature according to an independent testing protocol—currently International Organization for Standardization (ISO) 23537, though some older items followed European Norm (EN) 13537. Testing is based on a person wearing one base layer and a pair of socks, sleeping on an insulated surface with a minimum R-value of 5.38.
Each bag then gets 2 ratings: the Comfort rating is the lowest temperature at which the bag will keep the average "cold sleeper" comfortable, and the Lower Limit rating is the lowest temperature at which the bag will keep the average "warm sleeper" comfortable. Some brands determine their own temperature rating by aligning to the Comfort rating for women’s bags, to the Lower Limit rating for men’s bags, or somewhere in the middle for nongendered bags.
View all Sea to Summit Backpacking Sleeping BagsEach bag then gets 2 ratings: the Comfort rating is the lowest temperature at which the bag will keep the average "cold sleeper" comfortable, and the Lower Limit rating is the lowest temperature at which the bag will keep the average "warm sleeper" comfortable. Some brands determine their own temperature rating by aligning to the Comfort rating for women’s bags, to the Lower Limit rating for men’s bags, or somewhere in the middle for nongendered bags.
| Best Use | Backpacking |
|---|---|
| Tested Lower Limit | 18 degrees (F) - EN |
| Tested Comfort | 30 degrees (F) - EN |
| Temperature Rating (F) | 18 degrees (F) |
| Temperature Rating (C) | -8 degrees (C) |
| Shell | Nylon |
| Zipper Location | Left |
| Insulation Type | Down |
| Water-Resistant Down | Yes |
| Fill | 650-fill duck down |
| Lining | Nylon |
| Sleeping Bag Shape | Semirectangular |
| Stuff Sack Size | 7.5 x 14 inches |
| Stuff Sack Volume | 10 liters |
| Gender | Men's |
Buying Advice
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Most Helpful Favorable Review
Great first attempt
Long Spoon12 years ago
I used the Trek II this summer hiking the Oregon PCT. About 250 miles and it's holding up rather well; a grand total of one leaked down. Zipper is top notch with a nod to the ability to fully unzip...makes for a nice comforter-style blanket that's large enough to share.
The bag is ultra roomy without being overly heavy, something I thoroughly enjoyed as the mummy style for me is a bit too claustro. Never really tested the lower bound of the temperature rating, but I would never have noticed the freeze on a night camped above 7000ft if it weren't for the puddles. I'm right at 6' so the long seemed to be the logical choice. It fits well without too much room in the foot to keep my feet from warming up.
The shell did take a little moisture at the foot on some rainy nights when rubbing against the tent wall, though it didn't seem to effect the performance of the bag. Most other places seemed to bead and repel water readily.
Long Spoon
Willamette Valley, OR
29 people found this review helpful
Most Helpful Critical Review
Not up to par
Hendrix13 years ago
They had the right idea, which is why I bought it once and then gave a second one a try. Both were missing down, first in the upper chest baffle, second in the head. Making this bag completely useless in my book. Sent both back. First shot at Western Mountaineering did the trick. Anything but Sea to Summit for a sleeping bag, until they get it together.
Hendrix
Queens, N.Y.
11 people found this review helpful
EKloos23
Seattle, WA, United States
BEST BAG IVE OWNED
9 years ago
I currently own this bag and actually just purchased the Trek I as well. I have had zero (0) issues with bag. The zippers work flawlessly 99.9% of the time. The dual zipper system is awesome for a little extra ventilation. Sea to Summit included 3 bags with it. Its very soft and the loft is excellent. I do mostly summer camping and the Trek II was just too warm. So i got the Trek I also =) Its much roomier than a traditional mummy bag while still packing down almost as small. Ive read about some issues with parts of the bag missing down or even distribution but I've had none such issues. I literally have nothing negative to say about it. Get one!! You'll be glad you did!
Yes , I recommend this product
Long Spoon
Willamette Valley, OR
Great first attempt
12 years ago
I used the Trek II this summer hiking the Oregon PCT. About 250 miles and it's holding up rather well; a grand total of one leaked down. Zipper is top notch with a nod to the ability to fully unzip...makes for a nice comforter-style blanket that's large enough to share. The bag is ultra roomy without being overly heavy, something I thoroughly enjoyed as the mummy style for me is a bit too claustro. Never really tested the lower bound of the temperature rating, but I would never have noticed the freeze on a night camped above 7000ft if it weren't for the puddles. I'm right at 6' so the long seemed to be the logical choice. It fits well without too much room in the foot to keep my feet from warming up. The shell did take a little moisture at the foot on some rainy nights when rubbing against the tent wall, though it didn't seem to effect the performance of the bag. Most other places seemed to bead and repel water readily.
LKJones
Missoula, MT
Great sleeping bag
13 years ago
I bought this bag because of the lab verified temperature rating, the semi-rectangle shape, and its weight. The bag meets or exceeds every expectation I had for it. It is warm, it is light, it easily packs down to nearly nothing. In addition to the compression sack, the company included a storage bag (that keeps the bag secure but not compressed) and a laundry bag (if you decide you must wash it). The semi-rectangle shape is very roomy. Even at my not insignificant 5'11, 225 build I could turn over easily in this bag.
Yes , I recommend this product
Anonymous12
Rockville, MD
Great features
11 years ago
This is a well-thought out sleeping bag with some really nice features: -small storage pocket for essentials -unique zipper feature that prevents snagging -zipper at feet is separate to allow freedom/cooling if desired -bag can be opened completely to become a regular blanket -2 bags can zip together to be a "duo" sleeping bag for couples--if planning to do this, order one left-side zipper & one right-side zipper to make the duo symmetric; i have 2 left-side zipper bags which works well too, but by design it becomes somewhat asymmetric due to the hood. -3 storage bags came with the sleeping bag--compression bag, mesh/airy long-term storage bag & cotton bag for washing. -packs very small & light! We have used it for camping when the night temperature reached 35-40F and it definitely was warm enough. The only negative side (which makes this a 4.5 stars rather than 5 stars) was the down on the back side which was much thinner than expected even when it was in its unused/lofted state. Overall, very happy with the features & performance of this sleeping bag.
Yes , I recommend this product
Mike Camp
Austin Texas
Great Bag - Comfortable at 30 degrees
11 years ago
Really impressed with this bag. I was completely warm during a recent hike in Big Bend National Park up in the Chisos Mountains. Temperatures were in the low 30s. Everyone in my group was impressed with how small it packs up. I considered the TkI thinking the TkII might be too warm but I'm happy with my decision. It was comfortable in 45-50 degree temps too.
Yes , I recommend this product
AT Starchild
Taghkanic NY
Happy with this bag
12 years ago
I am very happy with this bag, I don't do well with mummy style bags and need the extra room of a semi-rec and this one features a lot but also packs down nicely and is good on it's weight and has a decent tempature rating that can take one into the warmer part of winter. There were also other reviews about the shell absorbing moisture, I have not noticed that as I spilt some water out of the jetboil onto my bag/pad and the water ran off the bag, it did not get absorbed.
Yes , I recommend this product
hscamping
Los Angeles, CA
if you want more leg room
6 years ago
This is an excellent backpacking sleeping bag for those who want more leg room than what a traditional mummy bag can offer. That was the main selling point for me. I'm a small guy, 5'4", but like to move around when sleeping and don't like the regular mummy bags. Used it on a couple of trips, nothing colder than 40F yet, nice and comfortable. It's duck down, and it does kind of smell like duck, but doesn't bother me. No hood, but not a big deal. Just wear a beanie if needed. Compression bag it comes with feels kind of small, but just keep stuffing it and then use the compression straps. Fits in the Atmos AG 65 backpack just fine.
Yes , I recommend this product
Anonymous
Gainesville, FL, United States
"Get-get.. get down!"
8 years ago
This is my first down bag and and is well designed. Semi-mummy design a good compromise between weight/volume and shoulder room. I really like that the bag can be opened at the feet to let fresh air in at the bottom of the bag. The bag can also be fully unzipped into a blanket! Although unzipping and zipping between blanket and bag mode might be frustrating in the tent. It features a mummy type hood that tightens via a drawcord on one side, or can be completely 'let out' so that it's not a hood (not as 'hooded' as others I've tried). I'm still not sure if I prefer this hood to traditional mummy hood.
peanut-b
Upstate New York
Very comfortable.
11 years ago
Compacts well and is lightweight for backpacking. Great comfy bag to get into after a long day on the trail. Pretty warm. I get very cold when I sleep and can't stand being confined in the top of the bag so I leave the top unzipped and wear a fleece. Given that, it keeps me decently warm. My husband has the same bag and cocoons himself and is very warm.
Yes , I recommend this product
TJF
SoCal
Great performance
10 years ago
I've only had this bag out about 20 times, in night time weather ranging from 18 to about 50 degrees, but long enough that I can form a opinion. Love. This. Bag. As one who loses his mind even thinking about the confinement of a mummy bag the semi-rec. cut is the perfect answer. Enough room to allow for some movement (as well as keeping things warm with body heat) but not so much that I notice cold air pockets. The LH zipper truly is "no-snag" and the hood is perfectly functional. It also packs down very small in the included high-quality compression sack although I will say that the sack itself is on the small side so it takes a little time to stuff. Not sure why that is given that it's a compression sack but it's hardly a deal breaker. The bag functions right down to it's temp rating, and probably below, as I've found myself peeling layers in the low mid 20's. But what's great about it is that you can unzip just the footbox to provide some air flow or the entire bag to create a quilt. That's a great option when the night time temps are on the warm side although I have had a little trouble zipping it back up on the two times I've unzipped it all the way. I'm sure that will come with practice. The TK2 also comes with a separate wash bag as well as a vented storage bag which is awesome. Score. I'm actually surprised the TK2 doesn't get more love on some of the gear sites considering how well it performs in addition to serving as a great option for those who can't deal with traditional mummies. A high five to Sea to Summit for this one. They nailed it.
Yes , I recommend this product
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