100% Cotton ?Use over regular sleepwear to take the place of loose blankets, helps establish good sleep habits and patterns. ?Ample Room for Kicking: Generous sack design allows room for kicking, so baby stays warm all night. Sleeveless design reduces the risk of overheating. ?Easy Diaper Changes: High-quality reverse zipper. Unzips from the bottom for easy diaper change Foot Openings Button for Easy Mobility. ?Provides parents peace of mind that their baby is getting adequate rest necessary for appropriate growth and take the place of loose blankets. ?Available here in Small Size, recommended for 8-12 month babies, if you have any question about the product, please do not hesitate to ask questions.