S: feet length 8",suit for US size 10.5-13.5 (Little Kids)
M: feet length 8.7" ,suit for US size 1-4 (Big Kids)
L: feet length 9.4" , suit for US size 5.5-8 (Big kids/women)
XL: feet length 10.2" , suit for US size 8.5-10(women)
Please check the measurement chart carefully before you buy the item.
If you have any question, please don't hesitate to ask me. Thank you very much!