More washed more soft. 6-layer cotton gauze, soft, cozy and breathable. Size: M: length: 27.5, suitable for baby height between 23-34, 0-2 years; L: length: 31.5, suitable for baby height between 30-38, 2-3 years; XL: length: 35.5, suitable for baby height between 34-43.(3-5 years. Recommended age and height in the size chart are for reference only) Detachable sleeves for 4 seasons. Vest-Type sleep sack for summer, and long sleeves for spring and autumn. Generous sack design allows room for kicking, but cannot be kicked off so child stays warm all night. Comfortable: zip for easy dressing and diaper changes.