COMPATIBILITY – Made with standard sized rails that are compatible with most seat post clamps. HIGH QUALITY MATERIAL - Soft and high-quality foaming material to provide a comfortable experience for children to eliminate possible sore bone pain.All materials are non-toxic and have been tested by CPSC. YOUNG RIDER FRIENDLY - Ergonomically designed to protect your child's young body and make your children enjoy happy riding. EASY INSTALLATION - Comes with mount, convenient and quick to install. 100% full refund or replacement if there is a problem. APPLICATION: Size: 8.7inch*7.5inch fits for 12 14 16 18 20 inch girls & boys bicycle.