How to Choose Sleeping Bags for Backpacking
Sea to Summit Trailhead ThIII 20 Sleeping Bag
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Great for weekend warriors and new campers, the feature-packed and value-oriented synthetic Sea to Summit Trailhead ThIII 20 sleeping bag is no slouch when it comes to performance.
Shop similar productsKey Details
Fill
Synthetic
Temperature Rating (F)
20 degrees (F)
- Tapered rectangular shape offers more space and comfort than a traditional mummy bag
- Full-length #5 YKK zip allows bag to open out flat and be used as a quilt
- Second zip slider in footbox offers versatile ventilation
- WaveLoftâ„¢ construction creates extra warmth and loft
- Lining fabric attached to shell prevents tangles
- Oversize zip draft tubes feature antisnag material
- 30-denier nylon shell treated with durable water repellent (DWR) and 20-denier nylon lining are lightweight and compressible fabrics
- Includes stuff sack
- Note: This bag is not designed to zip with another
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 | 20 degrees (F) - EN |
| Tested Comfort | 31 degrees (F) - EN |
| Temperature Rating (F) | 20 degrees (F) |
| Temperature Rating (C) | -7 degrees (C) |
| Shell | 30-denier nylon |
| Zipper Location | Left |
| Insulation Type | Synthetic |
| Fill | Synthetic |
| Sleeping Capacity | 1-person |
| Lining | 20-denier nylon |
| Sleeping Bag Shape | Semirectangular |
| Stuff Sack Size | Unavailable |
| Stuff Sack Volume | Unavailable |
| Compressed Volume | Unavailable |
| Gender | Unisex |
Buying Advice
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Adam
Who designs a sleeping bag that can't be put back into it's sack
4 years ago
Warm as rated, decent zippers. Roomy enough to be comfortable, but without carrying extra weight. HOWEVER, the bag simply cannot be put back into its sack UNDER ANY CIRCUMSTANCES, making the packed volume specification a total lie. Even machine packed by the factory this thing is really difficult to get out of the sack, and it's truly impossible to get back in. The headache this brings packing it back up every night is simply not worth it, so I returned it to the store and will buy a bag whose designers put a bit more thought into the user experience. Massive PITA to save what, 2g of extra sack weight for a sack that fits?
Originally posted on Sea to Summit
Christina B.
Not warm enough
1 year ago
I’ve used this bag three time and been cold every time. I’m an experienced backpacker with 20 years of experience in a lot of different bags. This does not preformed as advertised. I have the 20 degree bag and was cold at 45 degrees last weekend. I expected it to be less warm than my zero degree bag but not like this. It should be advertised as a summer bag only.
Originally posted on Sea to Summit
Bill
Love this bag for the price but I recommend also getting a liner
3 years ago
I'm not a hardcore backpack adventurer or anything, but I do love motorcycle camping, so I was looking for a low pack-volume sleeping bag that wasn't outrageously expensive. I'm also 6'1", 210 lbs. so I needed something roomy enough for me to be comfortable. This bag is super comfortable. It's soft and warm and packs down nice and small for stowing in my bike's luggage. I don't know why the reviewer Adam from Germany said it was impossible to get it back into the stuff sack, because I find it to be quite easy to get it back into the sack. It literally takes me about 60 seconds to roll the bag up and stuff it in the sack. I will say that if the temps drop into the 40s or lower, you're going to need a bit more than this bag can offer, so I'm going to get the liner to add that 10-15 degrees in case it gets a little chillier when I'm camping. But down into the 50s (Fahrenheit), with socks and sweats, I was toasty and slept great.
Originally posted on Sea to Summit
Annie H.
Good quality for the price
6 months ago
[This review was collected as part of a promotion.] As far a synthetic sleeping bags go, this one seems good for the price! We constructed & designed. On first use, I do not expect that this sleeping bag will actually perform well at its comfort rating, so if you're considering doing some serious winter camping, I would opt for a down sleeping bag maybe.
Originally posted on Sea to Summit
Mike Z
ohio
1 year ago
Bought this bag to use camping with my son's scout troop. It is quite roomy and comfortable. It kept me worm in an unheated cabin with outdoor temps reaching 16*F. I did sleep in pants, wool socks and a hoodie as well. This is a nice bag for guys like me- short and rather unathletic.
Age:35–44
Weight:250–275 lbs.
Height:5'8"
Yes , I recommend this product
Anonymous
Sufficient for an early fall trip to the Boundary Waters
5 years ago
Warm enough in mid -thirties, wearing wool clothes to bed, in tent in cool wet weather. Would not trust it below freezing (it's rated to 20F) Light and compact enough for the bottom of pack compartment. Sufficed for an early fall trip to the Boundary Waters.
Originally posted on Sea to Summit
Carl D.
Great bag
3 years ago
I've had many sleeping bags in 50 years of Scouting and this one was fabulous. It was light, compressable and very warm. Zipper was flawless. I paired it with a Reactor liner to provide comfort to even lower temperatures.
Originally posted on Sea to Summit
Thomas H.
Great 3 season bag
3 years ago
I bought this bag to replace my 20 year old bag which was rated at 20 degrees and served me well. The trailhead is significantly lighter, quality made, the zipper setup allows for good ventilation and packs well.
Originally posted on Sea to Summit
William W.
Only slept in it a
4 years ago
Only slept in it a few times, but this bag is awesome. Cool to the touch fabric on the inside, easy pull zippers with snags Only with overly quick or harsh use. Compresses and expands with ease.
Originally posted on Sea to Summit
Avery S.
Heavy, but very comfortable.
4 years ago
This is a bulky bag. I would reserve it for car camping/base camping. It’s too much to Cary. For the price there might be better options but it is certainly a very well made bag.
Originally posted on Sea to Summit