Desired fit can depend on experience and performance.
So iLL recommends those who use men's sizing to order a size and a half up. Example: If you wear a men's size 9 sneaker, select size M10.5 / W12. If you wear women's, So iLL recommends you to order your sneaker shoe size. Example: If you wear a women's size 9 sneaker, select size M9 / W10.5.