Down fill weighs less than synthetic and retains warmness better, but mainly costs more. Newer, more technically advanced sleeping bags often have water-resistant shells and can be absorbed in damper conditions. It is also recommended to keep a sleeping carry-on in a famed sack (storage sack) as opposed to the small traveling sack (compression bag) during lasting periods of storage. However, copious regular backpackers and hikers agree that hanging a sleeping bag, taking annoyance to change the locale of the haversack on the hanger at intervals so as to not build a "dead spot" (a spot where the fill has-been been crushed so that it is no more useful), is the best method of storing a packet for long durations.
Other materials, notably cotton and wool, have also been used for Sleeping Bags sleeping bags
