The pur flo sleep sac is designed to be used without the need for additional bedding with lining made from natural bamboo that is naturally antibacterial and absorbs 60 more moisture than cotton all the while feeling silky soft on baby s skin the anti allergenic and anti bacterial filling helps prevent build up of bacteria and dispels dust mites that are linked to asthma and eczema all of which help contribute to a peaceful nights sleep for baby and parents peace of mind features zip off r