The Halo® SleepSack® Swaddle replaces loose blankets in the crib that can cover your babys face and interfere with breathing. In addition to helping your baby sleep safer, it helps him sleep better, too. Its adjustable swaddle wrap immobilizes your baby's arms to prevent the "Moro" or startle reflex. And, it is the only 2-in-1 adjustable swaddle that allows for swaddling arms in or arms out for babys comfort and to ensure an easy and gentle transition to the SleepSack wearable blanket when it is time to stop swaddling. New, 100% cotton muslin is lightweight, soft and breathable.