She wears size Small -- this fit just fine. Ive been using them for close to two months for my workout and theyve lasted me ever since. My foot is between narrow and medium. Traditionally a perfect US W8 but had to go for the 39 to make sure my foot fit completely in the footbed. After having these shoes for 40 days and VERY minimal use (as seen in the above pictures), the sole separated from the shoe. It connects easily which is a BIG deal for him. It goes on the bottom & stick a seal on the top* Und die Riemen sind so straff, daß sie bereits nach wenigen Schritten extrem einschnüren. Great looking case but it is abit high priced, if you want your original case looking fresh then you would need this. , and the medium fit perfectly.