as a father of triplet I feel uniquely qualify to give the sleep sack a accurate review . I be not sure if we would have survive without it and we use small , medium , and large version as they grow from a few week to a year old . blanket be not safe to use with young baby , but it be still important to keep the little one warm and comfortable . these do the trick and be easier to manage than constantly wrap they . I would recommend to Halo that they upgrade they zipper . after significant use one in three malfunction make it difficult to suit up a wiggle infant .