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Head-to-head · Best Backpacking Sleeping Bags

Kelty Cosmic Down 20 vs NEMO Disco 15 Endless Promise Down Sleeping Bag

Which is the better buy? Side-by-side on rating, price, strengths, and watch-outs — with the published ratings we averaged to get there.

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The short answer

NEMO Disco 15 Endless Promise Down Sleeping Bag comes out ahead by a narrow margin (4.1 vs 4.0). NEMO Disco 15 Endless Promise Down Sleeping Bag is best for: Side sleepers and restless sleepers who want a roomy, warm down bag for car camping and shorter backpacking trips more than an ultralight one. Read the strengths below before deciding.

Kelty Cosmic Down 20
Ranked #4 in Best Backpacking Sleeping Bags
Kelty Cosmic Down 20
2 sources$209.95as of Sep 25

The Kelty Cosmic Down 20 puts real down in a budget bag, cut in a tapered mummy shape. Its 550-fill down isn't as thermally efficient as pricier insulation, so reviewers steer it toward summer camping and mild nights. The thicker shell fabric makes it tougher than ultralight bags, at the cost of weight and bulk. Casual backpackers who want down without the premium price will do fine; anyone expecting sub-freezing temperatures should look elsewhere.

Strengths
  • — More packable than most budget options with synthetic fill
  • — Relatively thick polyester fabric is more resilient than thin ultralight material
  • — Includes full-length draft tube and insulated collar for heat retention
Watch-outs
  • — Cut-rate 550-fill down places it at the low end for warmth-to-weight
  • — Runs colder than its temp rating
$209.95 · Check Price on AmazonFull review →
NEMO Disco 15 Endless Promise Down Sleeping Bag
Higher ratedRanked #2 in Best Backpacking Sleeping Bags
NEMO Disco 15 Endless Promise Down Sleeping Bag
2 sources$299.95as of Oct 16

The NEMO Disco 15 trades low weight for room to move. Its hourglass, spoon-shaped cut, zippered Thermo Gill vents and oversized draft collar won it an Editors' Pick from Better Trail, which called it one of the most luxe-feeling backpacking bags it has used. Better Trail and CleverHiker both stayed warm in it in freezing conditions, and both flag the same cost: it weighs about 2 lb 14 oz and packs bulky because of its 650-fill down.

Strengths
  • — Hourglass, spoon-shaped cut gives side sleepers room to change position, per Better Trail and CleverHiker
  • — Two zippered Thermo Gill vents release heat without opening the main zipper
  • — Kept testers warm on low-30s nights (Better Trail) and 15 to 20°F desert nights with a base layer (CleverHiker)
Watch-outs
  • — At 2 lb 14 oz it is one of the heavier backpacking bags Better Trail has tested in its class
  • — 650-fill down packs bulkier than 850-fill bags, so CleverHiker calls it a poor fit for ultralight or long-distance trips
  • — The roomy interior holds heat less efficiently than a closer-fitting mummy, per CleverHiker
$299.95 · Buy at nemoequipment.comFull review →

How they stack up

Kelty Cosmic Down 20

The Kelty Cosmic Down 20 uses 550-fill down where the Exped Terra 15 uses 650-fill and the Mountain Hardwear Phantom 30 uses 850-fill. At 2 lb 7 oz it weighs over a pound more than the 1 lb 6 oz Phantom 30, and it costs far less. It is a down bag where the REI Co-op Trailmade 25 uses synthetic insulation, and it is lighter than the Trailmade's 3 lbs 4.6 oz.

NEMO Disco 15 Endless Promise Down Sleeping Bag

The Disco 15 and the Exped Terra 15 both use 650-fill down and are rated around 15°F; the Disco is the roomier spoon shape. It is heavier than the Mountain Hardwear Phantom 30 (1 lb 6 oz) and Kelty Cosmic Down 20 (2 lb 7 oz), but lighter than the synthetic REI Co-op Trailmade 25 (3 lb 4.6 oz).

Specs side-by-side

SpecKelty Cosmic Down 20NEMO Disco 15 Endless Promise Down Sleeping Bag
Temperature Rating31/21°F (ISO Comfort/Limit)27/16°F (ISO Comfort/Limit)
Fill Power1 lb. 0.4 oz. of 550-fill down650-fill down
Weight2 lb. 7 oz.2 lb 14 oz
Insulation550-fill-power down—
Shell Fabric20D nylon20D polyester
Packed Volume10.7L14.9 L
Fill Weight—1 lb 7 oz
Shoulder/Hip Girth—62/57 in
Shape—Spoon (hourglass) mummy
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