NWT/ Box Happiest Baby 100% Organic Cotton SNOO Sleep Sack Size Small 0-2 months. SNOO Sack 5-Second Baby Swaddle. SNOO Sleep Sack is the ultra-soft, ultra-easy swaddle sack that helps babies be happier and sleep longer-and it's the only sleep sack that should be used with SNOO! Details: • The world's first ever 5-second swaddle • Made from soft and cozy 100% organic cotton • Attaches to SNOO with specially designed wings that help secure babies on the back • Double zipper that allows to zip from top or bottom for easy diaper changes • Special inner flaps keep even little Houdinis bundled all night • Extra-quiet Velcro, so light sleepers don't startle awake with diaper changes • Breathable mesh at shoulders and waist to reduce overheating • Perfect for healthy, growing hips. International Hip Dysplasia Institute seal of approval. • Arm openings can unsnap to allow babies to sleep with arms out