Stability Trainer - WaveSpring™ Technology Unlike traditional shoe midsole made primarily of foams, rubber compounds, or polymers, WaveSpring™ technology stores and disburses energy with every step. Testing performed by an independent source reports that 87% - 96% of the energy is returned from the WaveSpring™ The WaveSpring™ is laterally stable, lightweight, compact, and can easily fit into a typical shoe midsole. The technology is in the heel and forefoot of the shoe. As such, it has the appearance of a normal shoe. Looking from the outside no one will know you have a spring in your step but you! Traditional midsole materials work through compression and often breakdown quickly. The WaveSpring™ is mechanical. The spring will outlast the shoe. The wearer will have a new shoe feel from the first day its worn to the last! Tri-Spring Configuration