This is my upteenth pair of Shadow 6000: I've run two of my six marathons in them.  The shoe is one of the last shoes with a polyurethane midsole, which provides for me the best level of shock absorption: not overly firm with good rebound. You don't bottom out with these shoes. Provides a good base for my orthotics. But Amazon sat on my order for 5 days before shipping!  This is poor, unattentive customer service!!