US sizing. Tecton combines responsive cushioning in the midsole with carbon fiber plates, resulting in a firm running feel and energy return upon landing. A good choice when speed is needed! Compared to the previous version, this version 3 has a design in the carbon fiber plates that enhances stability, two layers of PEBA foam in the midsole, and a redesigned outsole pattern. The upper is made from durable Matryx fabric. On the manufacturers three-step scale, the Tecton falls on the side that emphasizes running feel and responsiveness, meaning there is no overly cushioned layer underfoot. - Made for neutral pronation - ProFlyX midsole features two parallel carbon fiber plates - "Early Stage Meta-Rocker" midsole quickens the transition from heel to toe-off - Toe protection - Convenient flexible collar keeps debris out - Heel-to-toe drop: 5 mm - Vibram Megagrip Litebase outsole with 4 mm tread Refer to the size chart for instructions on measuring your foot length and choose your siz