we begin use the Halo SleepSacks as soon as we son learn to roll over and could not be swaddle anymore . I love the soft , breathable cotton material . I can dress he in pajamas appropriate for the temperature \/ season know he will not be overheate with the cotton sleepsack on top . they be durable and wash well . I be happy that they come in x-large . my son be very tall for he age , but at 13 month he can still comfortably wear a sleepsack to bed . I think they be a safe alternative to blanket and more convenient for the child who toss and turn and would kick a blanket off anyway . as soon as we put on he sleepsack he be know it be bedtime . it be a great signal that end we bedtime routine .