NEMO Riff 15 vs REI Co-op Magma 15
In short: The REI Co-op Magma 15 costs $11 less; the NEMO Riff 15 is rated 11 °F colder on the figure each maker publishes; the REI Co-op Magma 15 saves 10.8 oz.
| Spec | NEMO Riff 15 | REI Co-op Magma 15 |
|---|---|---|
| Approx. price | ~$400 | ~$389 |
| ISO comfort | not published | 28 °F |
| ISO limit | 17 °F | 16 °F |
| Rating on the label | 15 °F | 15 °F |
| Honesty gap | — | 13 °F |
| Rating standard | ISO 23537 | ISO 23537 |
| Weight | 2 lb 7 oz | 1 lb 12.2 oz |
| Warmth per ounce | — | 1.13 °F/oz |
| Fill | 800 fill power down | 850 fill power down |
| Fill weight | not published | 15.9 oz |
| Loft budget | — | 13.5k in³ |
| Shape | mummy | mummy |
| Shoulder girth | not published | 63 in |
| Zipper | full | half |
| Shell fabric | Recycled polyester ripstop, C0 DWR | Pertex 15-denier ripstop nylon |
| Hydrophobic down | Yes | Yes |
| Packed size | 6.2 L | 5.2 L |
Shaded cells mark the row where one has a measurable advantage. Weight, thickness, girth and shape are left unshaded on purpose: heavier is sometimes tougher, wider is sometimes warmer, and calling a winner on those would be an opinion dressed as a measurement.
What each one does well, and costs you
NEMO Riff 15
- 800-fill down cuts four ounces and half a litre off the Disco at the same rated temperature.
- Keeps the Spoon shape, so it is still the side sleeper's bag — just a trimmer version of it.
- ISO lower limit of 17 °F published.
- Thermo Gills let a warm night be survived without unzipping the whole bag.
- $400 against the Disco's $300 for four ounces — the most expensive ounces in this catalogue.
- Only two lengths and no wide option, unlike the Disco's four sizes.
- Like every NEMO bag here, the ISO comfort figure is not published.
- The trimmer cut undoes some of the Spoon's point if you were buying it for room.
REI Co-op Magma 15
- Publishes both ISO figures, and the 16 °F lower limit lands within a degree of the name — the comfort figure is the one to plan around.
- 28.2 ounces with 15.9 ounces of 850-fill goose down, in the same ISO 28/16 bracket as Sea to Summit's Spark 15 for $160 less.
- Pertex 15-denier shell and lining, water-resistant down, a 63-inch shoulder girth and a 5.2-litre compressed volume — REI publishes all of it.
- Sold through a co-op with a real returns policy, which matters for a bag whose fit you cannot judge in a photograph.
- The 28 °F comfort figure is thirteen degrees off the 15 in the name — tied for the widest gap in this catalogue — so a cold sleeper should treat it as a high-20s bag.
- Reviews written before the 2026 revision describe a heavier, warmer bag; check the date before trusting a figure.
- Two lengths and one width, in left or right zip; there is no built-to-order width or overfill option.