Designed, developed and tested with the elite marathoners. For the serious athlete looking for the ultimate balance between light weight and support for racing the marathon. Very lightweight upper mesh panels add breathability. Soft frame offers supple feel and support. Reduced amount of seams provide comfort over 26.2 miles. Flat-profile Phylon™ midsole delivers cushioning and needed support for elite marathoners, perforated for 360 degree breathability. Heel Zoom Air™ unit for responsive cushioning. Full-length carbon rubber outsole brings durability with minimal thickness to save weight. Wt. 8.8 oz.