Featuring 18 innovative TPU polymer blades, the Springblade Razor powers your step by providing explosive energy with every stride. How is this possible? As you run, each blade traps energy as you step down and releases it on rebound, using stored energy for an explosive performance. Each blade has rubber, nonmarking tips that provide excellent traction and durability. For comfort, the synthetic TECHFIT upper has power bands across the forefoot and heel collar help you get a personalized fit. An external heel counter provides foot support. Each blade is calibrated to the specific size of the shoe.