Compare the documented Long and Long versions. This is a source-based specification comparison, not a field test or a current price ranking.
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The useful difference
Compare ISO comfort against ISO comfort only when both records provide it. A name such as 20°F and a lower-limit rating are different measurements. Fit and the pad beneath you can change the useful choice.
Exact versions compared
Kelty Cosmic Down 20 — Long and REI Co-op Radiant 20 — Long. Other sizes may change the result.
Specifications side by side
| Metric | Kelty Cosmic Down 20 — Long | REI Co-op Radiant 20 — Long |
|---|---|---|
| Name/label temperature | 20°F (-6.7°C) | 20°F (-6.7°C) |
| Comfort temperature | Not verified | 25°F (-3.9°C) |
| Limit temperature | Not verified | 13°F (-10.6°C) |
| Listed weight | 2.69 lb (1,219 g) | 2.88 lb (1,304 g) |
| Maximum listed user height | 78.0 in (198 cm) | 77.0 in (196 cm) |
| Shoulder girth | 64.0 in (163 cm) | Not verified |
| Fill power | 550 | 600 |
“Not verified” is an unknown value. It is never zero or proof that a feature is absent.
Search the exact model names on Amazon
These are paid search-result links for the model names above. Confirm the variant on Amazon before ordering.
Search for Kelty Cosmic Down 20 and check the exact size, revision and seller details before ordering.
(paid link)Search this model on AmazonAmazon search results may include different variants or sellers. No price or stock is verified here.Search for REI Co-op Radiant 20 and check the exact size, revision and seller details before ordering.
(paid link)Search this model on AmazonAmazon search results may include different variants or sellers. No price or stock is verified here.How to choose
Compare ISO comfort against ISO comfort only when both records provide it. A name such as 20°F and a lower-limit rating are different measurements. Fit and the pad beneath you can change the useful choice.
Open each record to inspect the source for the exact figure and its revision notes: Kelty Cosmic Down 20 — Long; REI Co-op Radiant 20 — Long. The comparison has 4 shared numerical fields. Consider your shelter floor, sleep position and expected conditions with the sleep system builder.
What this comparison cannot establish
Neither listing verifies live inventory, price, independent durability, noise, waterproof performance in a storm, or comfort for every sleeper. Where a manufacturer gives conflicting figures, the product record preserves the discrepancy and may omit a normalized number.
Sources and further reading
Source pages and product listings can change. Specifications were assembled from the supplied dataset as of October 30, 2026; current availability is not guaranteed.
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