This is a 3-piece set of 100% cotton swaddles (baby sleepers). The sizes are different, so you can size up as your baby grows, from newborn to about six months old. Although it may vary from child to child, my child often sleeps soundly through the night since starting to wear swaddles. It really helped us, as parents, to recover our energy at night without being exhausted. When purchasing, please research the proper use of swaddles and use them while observing your baby's condition m(_ _)m Thank you for looking.