In addition to helping your baby sleep safer, the HALO SleepSack wearable blanket helps your baby sleep better, too. It is a warm cuddly blanket they cannot kick off; ensuring baby sleeps soundly throughout the night. Use over regular sleepwear to take the place of loose blankets. Used in hospital nurseries nationwide, the Halo SleepSack wearable blanket is the number one choice of hospital nurseries, recommended by safety organizations and is recognized as "Hip Healthy" by the International Hip Dysplasia Institute. HALO supports non-profit organizations like First Candle/SIDS Alliance and The Canadian Foundation for the Study of Infant Deaths. 100 percent cotton interlock. Size small fits 10-18 lbs; size medium fits 16-24 lbs; size large fits 22-28 lbs; size extra large fits 26-36 lb sextra large fits 26-36 lbs.