1:When buying.Please choose size depend on inside length. And there is only CN size on shoes.Please refer to CN size when received the goods 2:we don't refund you if you choose wrong size,please choose size carefullly. 3:The way to choose perfect shoes for your children. Foot length+1cm=inside length. Such as Pls measure your kid's foot length as below.IF her/his foot length is 11.5cm,you can add 1cm.That's to say,choose inside length 12.5cm.Thank you for your support. 4:Because of different measuring methods,there may be about about 1cm error,belongs to normal.