95% Cotton+5% Spandex Imported Gown helps reduce the rise of overheating All different styles are with different Size Chart. Please read detail size measurement in Product Image before purchase. Use over regular sleepwear to take the place of loose blankets Foot openings for mobility when awake. Room to tuck in feet at night. Unzips from the bottom for easy diaper changes.?Generous sack design allows room for kicking, but cannot be kicked off so baby stays warm all night.