The HALO SleepSack wearable blanket replaces loose blankets in the crib that can cover your babys face and interfere with breathing. It is a warm, cuddly blanket that cannot be kicked off, ensuring little ones sleep soundly throughout the night. The HALO SleepSack wearable blanket is a trusted bedtime routine, providing a secure feeling while falling asleep. The Halo SleepSack Swaddle is the #1 choice of hospital nurseries nationwide. 100% polyester micro-fleece. 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.