The HIIT Trainer fits true-to-size. (from website) Bonus: our shoes are unisex, with men’s and women’s styles offering the same fit. This means sizes can be converted to suit a wider range of people. Men’s sizes are 1 full US size smaller than women’s. For example, if you are a women’s US 10, you can also purchase a men’s US 9 for a perfect fit. Plant-powered Knit Upper Responsive, Algae-based Cushioning Built for High Impact Moves