⚫︎ Free Size: Length (laid flat) approximately 30cm, suitable for ages 3-12. (For product information, it is listed as "17cm or more" due to input limitations.) Because it is a heel-less type, the length will vary depending on the foot size and leg length. For smaller children (approximately 3-6 years old), it will be over-the-knee socks, and for larger children (approximately 7-12 years old), it will be crew socks. ⚫︎ Material Composition: 75% Cotton, Polyester, Polyurethane ⭐️ Although it looks fluorescent in the photo, the actual color is a slightly more subdued, vibrant yellow-green.