The 5-Second Swaddle! This award-winning swaddle sack was created by Dr. Harvey Karp, America’s most celebrated pediatrician. Dr. Karp is the doctor whose 5 S’s started the Swaddle Revolution and he designed every detail of SNOO Sleep Sack with baby safety—and parent sanity—in mind. SNOO Sleep Sack is the ultra-soft, ultra-easy swaddle sack that helps babies be happier and sleep longer! Made with 100% organic cotton SNOO wings that keep babies safely on the back…for all naps/all nights Special inner arm bands and leg flap keep even little Houdinis bundled all night Perfect for healthy, growing hips (International Hip Dysplasia Institute seal of approval) Extra-quiet Velcro, so light sleepers don’t startle awake with diaper changes Breathable mesh—at shoulders and legs—to reduce risky overheating Arm openings that are easy to unsnap for babies who prefer their arms out Double-zipper—opens from top or bottom—for easy midnight diaper changes S : 5-12 lb M : 12-18 lb L : 18-26 lb Intended for use in SNOO only. | Happiest Baby Snoo Sleep Sack, White, Cotton, Large