Both sides are quilted soft fabric suitable for sensitive skin making it a beloved sleeping sack that cozies baby right to sleep. Top notch material feels like your favorite comfy bedspread and does not produce crazy static like fleece does and is not bulky just the right amount of thickness to keep baby warm for cooler nights or cold winter months. Once baby is showing early interest in rolling over starting with one or two arms out or baby does not like their arms being restricted in the swaddle it is time to ease the transition and this is a perfect in between step to keep them comfortable at night. This extremely high quality sleep sack is sturdy with well made and durable seams stitching and zipper and no loose threads and the tag is on the outside so you do not have to cut tags out that rub on baby foot or leg. The zipper fits nice and runs smooth with no catchy spots and the two way zippers make for easy on and off and easy for night time diaper checks.