Is the Kelty Cosmic 20 warm enough for freezing nights?

It is rated to 20°F, which most people treat as a survival limit rather than a comfort rating. For frosty nights, wear a base layer and use a pad with a good R-value.

How does it compare with a mummy bag?

The semi-rectangular shape gives more room at the shoulders and feet but is slightly less thermally efficient than a snug mummy. It suits side sleepers and campers who feel confined.

Is 550-fill down good?

It is mid-range down: warm and packable, but heavier and bulkier than 800-fill bags. It also loses loft faster if it gets damp.

What sizes does it come in?

It is offered in Short, Regular and Long, with the Long measuring 84 in and a 64 in shoulder circumference. Pick a length close to your height.

What is included with the bag?

It ships with a stuff sack and has a zippered internal stash pocket and a draft tube. A sleeping pad is not included.

How should I care for the down fill?

Wash it rarely, with a down-specific cleaner, and dry it thoroughly with dryer balls to restore loft. Store it loose, not compressed in the stuff sack.