Bi-directional Closure: delivers a semi-custom fit by gathering equally from both sides for even foot retention, with the precision of a micro-adjustable Boa reel Carbon fiber injected composite shank for efficient power transfer Low cut construction for a light, fast fit and feel Ethylene vinyl acetate X-Alp outsole/midsole for off the bike cushioning and comfort and on the bike power transfer Carbon rubber lugged outsole for superior traction and durability, SPD Compatible