Sizing: Fits large; purchase 1/2 size smaller than standard running shoe lengthHeel: MediumMidfoot: Medium to low volumeForefoot: Medium to narrowToebox Height: Medium to LowArch Structure: MediumShoe Shape: Curved The ON Cloudflash is a high performance racing flat built for the competitive road runner. Its lightweight and responsive design makes it a great option for 5k racing with versatility to go up in distance.