BackJoy's pelvic correction cushion with ventilation holes for a comfortable sitting experience. - Model: BackJoy - Material: Plastic - Color: Black - Design: With ventilation holes - Authentication: With QR code This item was used by a child for about six months. We chose the size based on weight, but it was too large for the child's bottom, so we are selling it. According to the official website, the regular size is for 50-135 kg. Recommended for those with larger bottoms. I think this size is for men who are "not" slender, rather than children or women. There are small scratches on the back (last photo), but there are no problems with use. Purchased from the Yahoo official website in 2024 and stored in a bag in the closet. Please feel free to comment if you have any other questions. Thank you for looking.