Sizing: Standard running shoe lengthHeel: Medium to narrowMidfoot: Medium to low volumeForefoot: MediumToebox Height: Medium to lowArch Structure: MediumShoe Shape: Curved As ASICS' firmest racing flat, the Tarther Kainos 3 offers a go-fast feel with a modern look that is best suited for running 5,000 to 10,000 meter races. Elite level runners may choose to wear this flat for longer distances up to the marathon.