these be great for when it be too warm for fleece sleeper , but too cold for no blanket . my only complaint be that even with closely follow the care instruction , we XL cotton sack seem to have shrink considerably . it just barely fit my 20-month old length-wise even though she be in the 50th percentile for height . even so , there be a gap in the market for product like this one , so I would consider this one to be a must-have . she will not keep a blanket on herself , so this be we only solution .