use our mesh stuff sack to organize the inside of your duvet. the stuff sack helps shape all of the old clothes, pillows and blankets to create a comfy mattress for the duvet cover. and when it's time for a wash, the stuff sack and all its contents can go right into the washer. 100% nylon, zippered, and gusseted to perfectly fit inside your molly mutt duvet. patented: uspn 8,342,126, 9,060,494