Therm-A-Rest Space Cowboy 45F/7C Sleeping Bag review: a sturdy and affordable synthetic bag for summer sleeping

For cozy comfort on warm nights where packability isn’t too much of an issue, this synthetic bag serves up dependable, durable performance

Julia Clarke in her Space Cowboy sleeping bag
(Image: © Julia Clarke)

Advnture Verdict

This good quality synthetic bag is a solid, and affordable, option for summer car camping where you’re not looking at frigid nights or worried about pack size, plus it stays warm even on dewey mornings


  • +

    Soft but sturdy material and construction

  • +

    Water-resistant insulation and quick drying

  • +

    Straps attach it to your sleeping pad

  • +

    Uses recycled materials

  • +

    Reasonably compressible and packable

  • +

    Good value


  • -

    Not as packable as a down bag

  • -

    Foot box might be a little tight

  • -

    Not super breathable

  • -

    Not suitable for cold nights

You can trust Advnture Our expert reviewers spend days testing and comparing gear so you know how it will perform out in the real world. Find out more about how we test and compare products.

Therm-A-Rest Space Cowboy 45F/7C Sleeping Bag: first impressions

Therm-A-Rest tout this sleeping bag as providing worry-free warmth, and at least for summer camping when rain or morning dew are an issue, that’s true. With a comfort rating of 52F/11C and a limit rating of 45F/7C, it does provide ample warmth for summer camping and it’s made from the same soft fabric we’ve come to expect from Therm-A-Rest. Because this bag is made using synthetic down, it has two major advantages: first, it’s quick drying and continues to insulate when wet, so there’s no need to worry about damp mornings, and second, it’s considerably cheaper than down alternatives in the same range.


• List price: $150 (US) / £125 (UK)
• Unisex: Yes
• Weight: 1lbs 10oz / 0.72kg
• Sizes available: Short, regular, long
• Materials: 100% Recycled Nylon RipStop w/ DWR,  eraLoft Polyester Hollow Fiber
• Comfort rating: 52F / 11C
• Limit rating:  45F / 7C
• Pack size: 14in x 8in
Colors: Celestial
Best use: Summer camping, car camping 

Now, synthetic bags don’t pack down as much as down, but this one comes in a storage sack that doubles as a stuff sack, and it’s certainly possible to take this backpacking, but the lack of compression straps mean it’s a little bulky, while the packed size is certainly no issue for car camping. The dual-purpose sack also means less materials are used in the production of this bag, which combined with the use of recycled materials makes for a kinder carbon footprint. A nice touch is the addition of two straps that connect to your sleeping pad to keep you from rolling off in the night, improving warmth and comfort. Anti-snag zippers help to improve the durability of this robust bag, and while we wondered if the foot box couldn’t be a little roomier, we think it’s great value for money if you’re seeking a good quality summer bag.

Therm-A-Rest Space Cowboy 45F/7C Sleeping Bag: in the field

Sleeping bag in a tent

Therm-A-Rest tout this sleeping bag as providing worry-free warmth, and at least for summer camping when rain or morning dew are an issue, that’s true (Image credit: Julia Clarke)

I’m still relatively new to synthetic sleeping bags, but they’ve certainly come a long way since the 1980s and I’m beginning to view them as a serious contender for camping, thanks to good quality bags like the Space Cowboy.

This sleeping bag is definitely designed for summer camping and this summer, we’ve had a lot of wet weather, so I’ve been quite happy to get to fend off the elements in a synthetic bag. This bag has a DWR finish that keeps dampness at bay, dries super quickly and most importantly of all, stays warm when wet so I haven’t spent the cool, damp mornings shivering away.

It’s not exactly packed with features, but one detail I really like are the two straps that connect it to my sleeping bag so that I don’t roll of it in the night and wake up cold and uncomfortable. In terms of the fabric and coziness, I generally find Therma-A-Rest’s sleeping bags to feel extra soft and this one is no exception. That said, I can’t help but think the foot box is just a tad too narrow for comfort, and I’ve noticed this before with their other bags. Of course, that means my feet stay toasty all night, but I feel I could benefit from an extra inch or two.

Space Cowboy next to a water bottle for scale

synthetic bags don’t pack down as much as down, but this one comes in a storage sack that doubles as a stuff sack (Image credit: Julia Clarke)

It comes with a storage sack that has two draw cords and doubles as a stuff sack. I like that this means less materials are used, plus the storage sack compresses it a little, which means it doesn’t take up so much room in my closet. It certainly doesn’t pack down as small as my down bag, and I can’t get it down as small as the advertised 10in x 8in but it still gets respectably small – compression straps would help.

It’s not the most breathable bag I’ve ever tried out, though it’s sometimes hard to tell with Scottish humidity, but fortunately in the summer I usually unzip my bag anyway. It’s a good quality bag and not nearly as fragile as my down bags, and despite its simple design I think it’s great value for money if you’re looking for a summer-only bag.

Here’s how it performed:


Cozy and soft fabric, but the foot box might be a little snug for some.


Plenty warm for summer camping, but not suitable for cold nights. 

Water beading on the Space Cowboy

The water repellent coating works a charm (Image credit: Julia Clarke)

Weather resistance 

Good DWR coating repels moisture and if it gets soaked, it’s fast drying and stays warm.


Doesn’t pack down as small as advertised, though you could use an existing compression sack with straps to help with that.


Not the most breathable sleeping bag out there, you might need to unzip and kick a leg out.


Anti-snag zipper, sturdy fabric and no leaking feathers ensure this will hold up against sharp sticks and rough adventures.

Julia Clarke

Julia Clarke is a staff writer for and the author of the book Restorative Yoga for Beginners. She loves to explore mountains on foot, bike, skis and belay and then recover on the the yoga mat. Julia graduated with a degree in journalism in 2004 and spent eight years working as a radio presenter in Kansas City, Vermont, Boston and New York City before discovering the joys of the Rocky Mountains. She then detoured west to Colorado and enjoyed 11 years teaching yoga in Vail before returning to her hometown of Glasgow, Scotland in 2020 to focus on family and writing.