Sleeping bags are essential equipment for outdoor camping and traveling. Their main function during camping is to keep warm, and the most important indicator of a sleeping bag is the temperature rating, also known as the comfort low temperature.
Down is further divided into duck down and goose down. Under the same conditions, goose down provides slightly better warmth retention than duck down. Down sleeping bags are relatively warm, easy to compress, and can easily retain their shape, with a relatively long service life. However, they have some drawbacks: they are relatively expensive, tend to absorb water, and a wet sleeping bag has rather poor warmth retention.