Swaddle Up M This is a summer-weight material, but since we kept the room warm even for our winter-born child, we rotated three of these with the regular material. Used for two children, one born in winter and one in summer. The soft, stretchy, thin material is easy to put on. Since the hands can come out, it's suitable for when the baby gets older. We used three size M swaddles in rotation, only at night. I am also listing other Swaddle Ups. If you purchase multiple items, I will discount each item by 50 yen.