About SNOO Sleep SackThe 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 cottonSNOO wings that keep babies safely on the back…for all naps/all nightsSpecial inner arm bands and leg flap keep even little Houdinis bundled all nightPerfect for healthy, growing hips (International Hip Dysplasia Institute seal of approval)Extra-quiet Velcro, so light sleepers don’t startle awake with diaper changesBreathable mesh—at shoulders and legs—to reduce risky overheatingArm openings that are easy to unsnap for babies who prefer their arms outDouble-zipper—opens from top or bottom—for easy midnight diaper changesWe’ve worked hard to think of it all!Colors: Rose Planets, Teal Planets, Midnight Planets, Graphite Planets, Ivory Planets, Ivory Planets with Black Wings, Graphite Stars, IvoryIntended for use in SNOO only.SNOO Sleep Sack Size GuideSmall: 5-12 lbsMedium: 12-18 lbsLarge: 18-25 lbsNote: SNOO Sacks and sheets sold separately. Click here for SNOO Sheets. Features: #1 Swaddle New York Times: Rated Americas best baby swaddle, our SNOO Sleep Sack was designed by top pediatrician and worlds leading hip-safe swaddling expert, Dr. Harvey Karp. Perfect for healthy, growing hips (International Hip Dysplasia Institute seal of approval).|100% Organic Cotton: Made from luxuriously soft organic cotton with special wings that attach to our SNOO Smart Sleeper to keep babies safely on the back. Includes extra-quiet Velcro for escape-proof security and 2-way zipper that opens from top or bottom for easy midnight nappy changes.|More Infant Sleep: Our baby swaddle sleep sack prevents startles and boosts babies sleep quality with special inner flaps that give the snug embrace your baby boy or girl loved in the womb. Arm openings can unsnap to allow for arms out. Great transitional swaddle for moving to crib with arms free independent sleep training.|5-Second Baby Swaddle: The Happiest Baby Swaddle is the easiest, safest, fastest, escape-proof baby swaddle wrap. It promotes self-soothing and keeps babies sleeping longer than other swaddles.|Prevents Overheating: Breathable mesh at shoulders and legs of baby warp reduce risky overheating. More secure and comfortable than other swaddlers, blankets, or baby sleepers.