HALO® created the first SleepSack® over 20 years ago with both safety and comfort in mind. The #1 choice of 1,700 hospitals in the United States, our original wearable blanket with sleeveless design nestles baby like a soft blanket without the risk of Sleep-related dangers. #Signature "Back is Best" embroidery is a gentle reminder to place baby in the recommended Sleep position. #Features a 2-way zipper for easy diaper changes and a roomy Sack design that's recognized by the International Hip Dysplasia Institute as promoting healthy hip development. #Use over regular sleepwear to take the place of loose blankets #micro-fleece TOG:1.0 Size small fits 10-18 lbs; size medium fits 16-24 lbs; size large fits 22-28 lbs