Sole material: rubber Function: Lightweight, non-slip, wear-resistant The sole is made of a soft, non-slip design and material. The lightweight footbed has arch support and provides cushioning for all-day comfort. Flexible TPR outsole provides grip and traction on varied terrain. Comfortable: the soft, lightweight and sturdy sole is designed to be perfect for new walkers playing indoors, and the non-slip sole is carefully crafted to make walking feel natural. You can put them on yourself: the sandals are closed with Velcro on the sides and ankles. Children can easily figure out how to put them on, so the sandals are very easy to put on. This style of sandal frees up parents' time and allows children to practice their hands-on skills. Shoe sizes: Size 21 = 13.5 cm Size 22=14cm Size 23=14.5cm Size 24=15cm Size 25=15.5cm Size 26=16.5cm Size 27=17cm Size 28=17.8cm Size 29=18.5cm Size 30=19cm