There is something indescribably cozy about being curled up in a warm sleeping bag when its cold out. I was doing that in the back of my truck, watching raindrops run down the window outside, comfortably swaddled in my NEMO Coda Endless Promise Mummy Sleeping Bag.

　　It was 8:00 a.m. Temps were probably approaching the mid-40s now, but that night, it had easily dipped into the 30s at Twin Lakes, Colo. It could have gotten even colder and I would have been just fine. My bag was rated down to 10 degrees (20-degree comfort) — overkill for most summer camping trips, but there had been a couple of cold snaps where Id been glad to have it.

　　This particular morning was one of them. But this bag isnt just warm; as part of NEMOs Endless Promise line of sleeping bags, the Coda represents NEMOs first fully recyclable line of down bags. It uses ALLIED Feather + Downs (AF+D) 100% ethically sourced and traceable down. And, when the bag reaches the end of its useful life, AF+D will remove the insulation and reuse it. And NEMO will recycle the rest of the bags mono-polymer components.

　　That novel concept was the hook that reeled me into testing this bag. Ive been using the Coda from late spring through summer and will continue using it into fall. Its still many years from being recycled, but recyclability aside, this ultralight sleeping bag is a solid, well-designed piece of gear.

　　In short: The NEMO Coda Endless Promise Down Mummy Sleeping Bag is one of the brands first fully recyclable ultralight down sleeping bags. It comes in two temperature ratings — 10-20 and 25-35 degrees (limit-comfort) — it packs easily, and the hydrophobic down will retain some insulation properties even if water gets past the DWR coating of the shell and liner. The Coda also represents the first generation of NEMO bags using AF+D insulation that is fully traceable and reusable. When this bag reaches the end of its life, and you can send it back to NEMO, and the brand will recycle the entire thing for you.

　　If you want to compare the NEMO Coda to other ultralight sleeping bags, check out GearJunkies guide to the Best Backpacking Sleeping Bags.

　　NEMO Coda Endless Promise Down Mummy Sleeping Bag

　　(Photo/NEMO) Specs Minimum weight 2 lbs., 3 oz. Packed weight 2 lbs., 5 oz. Packed size 11.0 x 7.5 dia. Fill type 800 FP Fill weight 1 lb., 6 oz. Fits up to 56 (short); 6 (regular); 66 (long) Shoulder girth 59 Hip girth 54 Knee girth 46 Compressed volume 4.8 L Shell fabric 100% recycled polyester ripstop w/ C0 DWR Lining fabric 100% recycled polyester taffeta w/ C0 DWR Color Goodnight Gray Zipper location Center Pros Ultralight and very packable DWR coated liner and shell Fully recyclable Traceable down Cons Zippers catch very easily Shell material is not very durable Will Brendza Check Price at BackcountryCheck Price at NEMO NEMO Coda Endless Promise Sleeping Bag Review GearJunkie reviewed NEMOs first Endless Promise Sleeping Bag, the Forte, when it was released in 2023. That bag uses synthetic insulation and is completely made of recyclable polyester materials.

　　Endless Promise recyclable down sleeping bags are a new lane for NEMO, though. It partnered with AF+D to be the first brand to use its innovative down recycling program in 2024.

　　When Endless Promise down bags are recycled, AF+D pulls the ethically sourced insulation out and funnels it into its RENU:TRACE program. RENU:TRACE uses it to make what it claims is the worlds first fully circular and traceable recycled down insulation.

　　(Photo/Will Brendza) NEMO can then break down the bags other components and turn them into Repreve polyester yarn to make something new.

　　Its the first time people wont have to choose between ethically sourced down or 100% recyclable synthetic insulations. They can get both in a single bag. Thats why the Endless Promise line of down bags recently won the Green GOOD DESIGNaward for sustainability in design.

　　Overview Some people dont like mummy-shaped sleeping bags. I find them comfortably confining, and theyre my preference for backpacking. So I was excited to see an ultralight down mummy sleeping bag from NEMO.

　　Some people might knock it for being a darker color, as brighter colors are better for visibility in an emergency. But I wont. I like the understated Midnight Gray NEMO used.

　　One of my favorite features of this bag is the Thermo Gill vent. It has an inside zipper and an outside zipper that helps control the temperature. If I was overheating, I could open one or both of the zippers all the way or just partially and really dial where I was most comfortable.

　　(Photo/Will Brendza) The center zipper can also be used for ventilation, and I opened it as well as the Thermo Gill on a couple of the warmest nights. It only runs about two-thirds of the way down (like most mummy bags), so dont expect to use the Coda as a quilt. There is, however, another zipper at the very foot of the Coda. That can be opened up for extra ventilation or to put on/take off socks.

　　The hood is generous, and a cozy internal draft guard keeps cold air from sneaking in around your neck and shoulders. A hood cinch pulls the hood snugly and evenly around your head and face.

　　The Coda bags shell and liner are coated with DWR for water repellency, and the PFAS-free, RDS-certified 800 FP down is itself hydrophobic. That means that water has a hard time getting to the insulation, and even if it does, the down will retain its loft and insulating properties (to a point).

　　In the Field

　　(Photo/Will Brendza) Warmth Weight I tested the Coda Endless Promise sleeping bag on several overnight camping trips, a 4-day horseback hut-to-hut trip, and a 3-day backpacking tip — all in the Colorado Rockies in spring and summer. On the cold end, temps got down to the 30s at night. On the high end, nighttime temps hovered in the 50s.

　　The 10-20-degree bag was too hot for most of these conditions. But in spring and late summer, its been welcomed warmth. Getting into fall and winter, it will be even better suited.

　　If you primarily camp in the summer, the 25-35-degree Coda would be a better option.

　　(Photo/Will Brendza) Weight-wise, the NEMO Coda is suitable for backpacking. Compared to those on our Best Backpacking Sleeping Bags, the Coda lands on the heavier end of the spectrum, with only four bags weighing more.

　　I never found the Codas weight to be an issue, but Im also admittedly not a dedicated gram counter.

　　Vents Features The Thermo Gill is a nice feature that I used frequently. I almost never had it completely closed. But I fiddled with different combinations, unzipping the outer zipper all the way and the inner halfway or keeping the inner zipper up and having the outer unzipped completely. It did give me nuanced control of how much heat I was dumping.

　　(Photo/Will Brendza) Footbox zippers always earn a sleeping bag points in my book. Theyre extra ventilation and allow you to walk around in the morning, still wrapped up in your bag. I like popping on a pair of slippers with my bag on and drinking a cup of coffee when its still early enough to see my breath. You can do that in the Coda.

　　However, the tapered mummy shape and relatively short zipper opening mean youll be shuffling around more than walking.

　　The hood on this bag is large and easy to find. Between the draft collar and the cinch system NEMO used, you can almost entirely encase yourself in this bag. For very cold evenings this fall and winter, I anticipate those will be very welcome features.

　　Carbon Questions I will preface this section by saying that more outdoor gear should be recyclable. Innovating systems and partnerships to make that happen is the only way to move the industry in a more sustainable direction — even if it means balancing carbon costs.

　　(Photo/Will Brendza) Recycling an endless promise down sleeping bag undoubtedly generates some level of carbon. Plus, customers have to ship the bag back, and AF+D has to remove the down. Finally, NEMO has to send the other components to a recycler that can make new polyester yarn out of whats left.

　　How does all that compare to the carbon cost of just making a new sleeping bag?

　　NEMO has not yet gotten back to me with an answer to that question. But when it does, I will update this section of the review.

　　Regardless of NEMOs answer, though, the Endless Promise line of sleeping bags from NEMO represents a big step toward sustainability. Recycled bags will keep some plastics out of landfills and allow for the reuse of down insulation. And, as with all technologies, the capital and carbon costs of the recycling process will come down over time.

　　Room for Improvement I only had one real gripe with the NEMO Coda Endless Promise Down Mummy Sleeping Bag: the zippers. I get it —NEMO is creating an ultralight product thats fully recyclable. There were probably only so many zipper designs that fit the bill.

　　But I had almost constant issues with the zippers (especially the main center zipper) catching on the shell or liner material. It was almost every time I zipped or unzipped this bag, Id get only part of the way down, and it would get stuck.

　　On a few occasions, when I woke up bleary-eyed and still half asleep to use the bathroom, that was a frustrating problem.

　　(Photo/Will Brendza) Eventually, I did tear a hole in the sleeping bag because of this issue. When I asked NEMO about it, the brands head of customer service said it had never come across their desk and that the brand rarely gets warranty/repair tickets for the Coda.

　　Maybe Im just hard on gear. Maybe you wont have this issue. But if you do, and you rip your bag, I fixed the hole in mine pretty easily with some repair patches.

　　NEMO Coda Sleeping Bag: Who Is It For?

　　(Photo/Will Brendza) If you are in the market for a backpacking sleeping bag and you are an eco-conscious person who values sustainability, you should check out the NEMO Coda. Its a solid sleeping bag designed by a respected brand thats innovating fully recyclable outdoor gear. That is cool. I wish more brands were putting that much effort into being green.

　　Even if sustainability is not a priority for you, and you just want a well-designed backpacking sleeping bag, I still recommend at least considering the Coda as a comparison as you shop. This bag — minus all of its sustainability — is still a very strong product. The water resistance inside and out, hydrophobic 800 FP down, ventilation options, and heat-trapping capability make this a powerful contender among comparable bags.

　　Ive enjoyed using the Coda this summer. I might even throw it in my pack for a few overnight hut skis this winter. Despite my disagreements with the zipper, this recyclable down bag impressed me. Its earned a spot in my shoulder-season backpacking kit.

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　　Will Brendza Check Price at BackcountryCheck Price at NEMO