HALO SleepSack wearable blanket: The Safer Way to Sleep The HALO SleepSack wearable blanket replaces loose blankets in the crib that can cover your baby s face and interfere with breathing. 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. Used in hospital nurseries nationwide, the Halo SleepSack wearable blanket is the #1 choice of hospital nurseries and is recognized as "Hip Healthy" by the International Hip Dysplasia Institute. HALO also proudly supports non-profit organizations like First Candle/SIDS Alliance. Use over regular sleepwear to take the place of loose blankets. 100% polyester micro-fleece. TOG: 1.0. Size preemie fits birth-5 lbs; size small fits 10-18 lbs; size medium fits 16-24 lbs; size large fits 22-28 lbs; size extra large fits 26-36 lbs.