the only criterion is barefoot length.
if foot is wide, choose bigger size.
CHECK SIZES:
size39 =barefoot length 24.1-24.5cm
size40 =barefoot length 24.6-25cm
size41 =barefoot length 25.1-25.5cm
size42 =barefoot length 25.6-26cm
size43 =barefoot length 26.1-26.5cm
size44 =barefoot length 26.6-27cm
size45 =barefoot length 27.1-27.5cm
