Spark Ultralight Sleeping Bag

The 45° S2S Spark is a lot more expensive but it compresses to 2.4 L. https://seatosummit.com/products/spark-down-sleeping-bag

\> Sea to summit spark 15 (EN rated -1.6°C). On sale now. Won't it be too tight? I have tried both a regular Spark 15 in the store, and a Spark Pro 15 (both in Long versions, as I'm 194 cm tall), and they are surprisingly roomy. I am a big guy at 116 kg, and I can roll onto my side inside the bag and throw my legs around. For comparison, I have tried getting into a Nordisk Passion Five XL bag too, and it wouldn't even close around my shoulders. I went with the Spark Pro 15 for the better down (so an extra degree of warmth) and additional features, but could as well been happy with the regular one. Already tested the bag out camping, and those features came in handy from flexibility standpoint - it was toasty with only 12C outside, so I opened it into a quilt and was very comfy all night. I'll be going to the Carpathians next week to sleep at 1500-1700 masl elevations and I think 3-7C degree temps, so I can share my experience afterwards, if you'll still be interested by then.

Really no way of knowing if it will fit. For me at 194 cm tall, the 198 cm Long versions of Sparks fit just enough to fit a "regular" sized aeros pillow inside the hood. If you put your pillow outside, you're probably gonna be alright with a regular length.

Only thing I can comment is I have the 0F spark and its very good, though overkill for your use. I use it for winter outings

I have the spark, comfort -1 and -9 women’s specific, I love it, it’s tiny and lightweight silky soft and as a cold sleeper it lives up to its -1 rating.  Biggest worry is that the toe box and head are water resistant but the main body of the bag isn’t, though I’ve not had any wet feathers from condensation, the main body does bead, if you get a lot of  it in your tent I’d worry about it. I generally air my tent for a while whilst getting breakfast and coffee etc.. and dry it off with a micro towel, but if you are a quick starter in the morning I can see stuffing the bag into its sack wet being a problem.  Also you can see the feathers through the yellow sections of the bag, which some people may find grim.  The zip on it is great, and I would definitely recommend.  Owned the -9 for 6months and the -1 for two so not a long term review 

I have the spark, comfort -1 and -9 women’s specific, I love it, it’s tiny and lightweight silky soft and as a cold sleeper it lives up to its -1 rating.  Biggest worry is that the toe box and head are water resistant but the main body of the bag isn’t, though I’ve not had any wet feathers from condensation, the main body does bead, if you get a lot of  it in your tent I’d worry about it. I generally air my tent for a while whilst getting breakfast and coffee etc.. and dry it off with a micro towel, but if you are a quick starter in the morning I can see stuffing the bag into its sack wet being a problem.  Also you can see the feathers through the yellow sections of the bag, which some people may find grim.  The zip on it is great, and I would definitely recommend.  Owned the -9 for 6months and the -1 for two so not a long term review 

Spark 0 is great. Used it down to 8F this winter and was still toasty warm

I’ve got a Sea to Summit Spark II, which is excellent - I’ve used it for random tramps, and bikepacking events like the Great Southern Brevet, Kiwi Brevet, etc. One night, we had torrential rain and snow come through, and I was fine in the bag (this was in an open fertiliser shed/lean to in Central Otago) OGR has huts, so minimum temp isn’t such a problem, and if you’re looking for a good 3 season bag, something similar to the Spark II would be a good bet (they’re no longer made, from what I can tell). Mine is ~10 years old and just as good as the day I bought it, which is why I recommend the brand. Also worth looking for a decent sleeping mat - it’ll make as much difference as a good bag, if it’s insulated. I use a mummy shaped Exped mat, rolls up about the size of a bidon and weighs ~400g. IMO it’s worth investing in a good sleep system, I’ve had my stuff long enough that it has cost $100/year at this point.

I’ve had my Sea to Summit Spark II for a decade now and it has served me well. I also run cold and hate cold camping (anything under 35F, I’ve camped in 19F in the past and nah, I’m good). It is definitely ultralight with an exceptionally small pack size! In tandem with a silk liner, my “camping” puffy jacket that’s not so puffy because it’s lost half its feathers and therefore packs down smaller, thick wool socks that are *only* for camp, and some thick cashmere joggers and I’m good to go for 30-40F. 99% of my camping is by way of bicycle, so pack size is the ultimate make or break attribute to my gear selection.